Chocolate-Covered Caramel-Filled Shortbread Cookies (a.k.a. Homemade Twix) Recipe

High-quality dark chocolate, buttery homemade caramel, and crisp, flavor-packed shortbread make these better than Twix.

Filling the shortbread base of DIY Twix with caramel sauce.
The classic flavors of Twix improved with better ingredients.

Serious Eats / J. Kenji Lopez-Alt

Why It Works

  • Combining oat flour, cornstarch, and regular all-purpose flour gives us shortbread cookies with a crisp texture and plenty of flavor.
  • Real butter, cream, and brown sugar make for a flavorful caramel. It stays soft with the help of corn syrup.
  • Tempering the chocolate with either a food processor or a sous-vide circulator ensures excellent snap and texture in the finished cookie.

Just because something's your favorite doesn't mean that it can't be improved upon. The Beatles woulda been better had Magical Mystery Tour never appeared in their catalogue. Any given bathtub could be improved by making it just an inch deeper. My wife could improve by... er, on second thought, better not go there. But you get the idea.

Twix candies on a plate
A classic Twix.

Serious Eats / J. Kenji Lopez-Alt

Likewise, Twix—the classic caramel-topped, milk chocolate-covered shortbread cookies—have always been my favorite candy bar, but it's easy to see where there's room for improvement. The shortbread is crisp enough to do its job, but it could have a more robust flavor and more short (i.e., crumbly) texture. The caramel layer could benefit from the addition of real butter instead of the flavorless palm oil you'll find on the ingredients list. And then there's the chocolate. Not that I don't appreciate Mars' super-sweet milk chocolate, but wouldn't it be nice if that cookie and caramel could come enrobed in, shall we say, the more adult flavor of high-quality dark chocolate?

Cross-section of DIY Twix
Twix v2.0.

Serious Eats / J. Kenji Lopez-Alt

That was my goal this holiday season: a cookie that packs in everything I love about Twix, but with higher quality, more flavorful ingredients. Twix, v2.0 if you will.

The Cookie

Of course, Twix didn't invent this flavor combination. In bar-form, it's known as Millionaire's shortbread, though this variation produces individual round cookies—a much more elegant approach for the holidays, I believe.

First step: improving the cookie. Classic Twix are made with a shortbread biscuit that is not much more than sugar, wheat flour, and palm oil. For my version, I knew I wanted something with a little more flavor. This buttery short bread recipe I developed for Cook's Illustrated (warning: pay wall) back in 2009 was a great place to start.

Rather than plain wheat flour, the dough incorporates some oatmeal that I grind to a fine powder in a blender or spice grinder, giving the finished shortbread a much more interesting flavor. A touch of cornstarch mixed into the dry ingredients also ensures that the cookies come out crisp and tender, rather than tough and dense.

A mound of shortbread dough on parchment paper

Serious Eats / J. Kenji Lopez-Alt

It's a super simple dough to make: just combine the powdered oats, flour, cornstarch, confectioners' sugar, and a pinch of salt in a stand mixer, then beat in butter until it forms a cohesive dough.

Typically, you'd press the dough into a round pan with your fingers to shape it, but for these cookies, I figured rolling and cutting the dough out would work better. With a plain rolling pin, the soft dough ends up sticking and tearing. Instead, I rolled out the dough between sheets of parchment paper.

It's easy to get the dough out to a thin, even layer this way. I aimed for cookies about 3/16th of an inch thick. Seems pretty thin for a cookie—particularly a Twix imitator—right? But there's method to the madness.

Before I started, I figured there were two basic approaches to a caramel-filled cookie I could go with. The easier of the two is a thumbprint-style cookie, where you make a small ball of dough, then press it down in the center with your thumb, forming a well. This method is okay for casual cookies, but I wanted something that looked a little more refined on my holiday cookie spread.

The second method is better suited for that: filling them like linzer cookies.

Punching out disks of shortbread dough from a thin sheet of dough.

Serious Eats / J. Kenji Lopez-Alt

With this technique, you cut out an even number of circles with a cookie cutter, then cut a smaller circle out of the center of half of them.

And while with classic linzer cookies you'd bake the circles and rings separately, filling and combining them after baking, I found it was much better to lay out the circles then top them with the rings before baking. (Be careful, those rings of dough are pretty delicate.)

Laying dough rings on top of dough disks

Serious Eats / J. Kenji Lopez-Alt

By pressing down slightly on the rings, you end up with a completely solid shortbread cookie with a nice, deep, circular well in it (the scraps of leftover dough can be re-rolled to cut out more cookies). And because shortbread cookies are completely unleavened, they don't change their shape at all while baking. At least, I thought they wouldn't. In reality, they puffed up a bit in the center, ruining those wells I'd constructed. Docking them with a toothpick just before baking created channels for steam to escape, solving that problem.

I start the cookies in a hot 450°F (230°C) oven, which gets them to begin to set before dropping the temperature to 300°F (150°C), which allows them to cook through completely until crisp and lightly golden brown.

The Caramel

Next up, the caramel filling. There are a number of different ways to make chewy caramel that stays soft at room temperature. The easiest by far is to simply buy some high-quality caramel candies, microwave them in the oven until melted, then pour the melted caramel into the cookies. But that'd be cheating (I won't tell if you don't).

If you want to go from scratch, however, you've got two basic techniques. Both require a good thermometer. The first is the classic technique, in which you first make a sugar caramel by heating sugar, corn syrup (corn syrup is an invert sugar that helps prevent re-crystallization down the line), and water in a saucepan until it darkens in color. Once it hits the right shade, you whisk in some butter and heavy cream and reheat it to 245°F (118°C) before stirring in some vanilla and pouring it into the cookies.

This method is a little finicky. First off, there's the crystallization problem. While the sugar is caramelizing, if you drop even a few specks of hard, crystallized sugar into the melted sugar (say, the sugar that's clinging to the edges of the pot), the entire pot will rapidly seize up, requiring you to start over again from scratch. It also requires you to use your thermometer twice, once during the caramelization, and once after adding the butter and cream.

A much easier, more foolproof, and—to my mind—tastier method is to utilize protein-packed, already-been-cooked sweetened condensed milk. With this method, all you have to do is combine the condensed milk, some sugar (I use a mix of white and brown), butter, corn syrup, and salt in a pot and heat it up to 245°F before stirring in some vanilla (adding the vanilla at the end keeps its flavor bright). No chance of crystallization, you only need to monitor the temperature once, and I actually really like the flavor condensed milk brings to it.

Once the caramel is made, I spoon it into the center of each cookie, letting it rise up above the edges a little bit. Any excess caramel can be set in a buttered casserole dish and cut into individual candies after cooling at room temperature for a couple hours.

The Chocolate

Once the caramel is set, we're at the last stage, and for this, I don't need to tell you twice that a good quality dark chocolate is what you're going to want to use.

In order to get your chocolate to set up with a nice glossy finish, melt-in-your-mouth-not-in-your-hand qualities, and a decisive snap, you'll need to temper it by melting it, then precisely controlling its cooling process to form the right type of crystal formation in the cocoa butter. I already spent many hours and about 5,000 words explaining the hows and whys of tempering chocolate so I won't bore you with the details here, but do read up on it if you're interested.

The short version? Melt your chocolate at 115°F (46°C), cool it to 85°F (30°C) while adding some fresh, unmelted chocolate to it and stirring vigorously, then reheat it to 90°F (32°C). It should come out nice and pourable.

Pour the chocolate over the cookies while they rest on a wire cooling rack to allow the excess to drain off onto a sheet of parchment paper below. A few quick raps of the tray on the counter will get you a thin, even layer of chocolate over each cookie. Exactly what the doctor ordered.

I don't know about you, but I enjoy the flavor of good coarse salt with both chocolate and caramel, so it seems like a logical addition to these cookies before the chocolate solidifies (which, if it was tempered properly, should be just a matter of minutes).

Chocolate coated DIY Twix with sea salt.

Serious Eats / J. Kenji Lopez-Alt

Don't those look pretty?

Plateful of DIY Twix cookies.

Serious Eats / J. Kenji Lopez-Alt

I'm not really much of a sweet tooth, but it's pretty hard to keep your hands off of these when there's a whole plate of them on the table and you know what's hiding under that chocolate.

A bite taken from DIY Twix cookie showing cross-section.

Serious Eats / J. Kenji Lopez-Alt

Make sure to make twice as many as you think you're gonna need, because just like Twix, these cookies are best enjoyed in pairs.

December 2014

Recipe Facts

3.8

(4)

Active: 2 hrs
Total: 3 hrs
Serves: 24 servings

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Ingredients

For the Shortbread Cookies:

  • 2.5 ounces (1/2 cup) steel cut oats

  • 7.5 ounces (1 1/2 cups) all-purpose flour

  • 1.5 ounces (1/4 cup) cornstarch

  • 3 ounces (2/3 cup) confectioners' sugar

  • 1/2 teaspoon salt

  • 7 ounces (14 tablespoons) unsalted butter, cut into tablespoon-sized pats

For the Caramel Filling:

  • 6 ounces (about 3/4 cupsweetened condensed milk

  • 3 ounces (6 tablespoons) unsalted butter

  • 4 ounces (about 1/2 cup) white granulated sugar

  • 4 ounces (about 1/2 cup) dark brown sugar

  • 4 ounces (about 1/2 cup) corn syrup

  • 1/4 teaspoon salt

  • 2 ounces (about 1/4 cup water)

  • 1/2 teaspoon vanilla extract

For the Chocolate Coating:

  • 24 ounces bittersweet chocolate disks, chips, or roughly smashed bars

  • Coarse sea salt such as Maldon

Directions

  1. For the Cookies: Adjust oven rack to center position and preheat oven to 450°F (230°C). Place oats in a spice grinder or blender and process to a fine flour, about 1 minute. Combine oat flour, regular flour, cornstarch, confectioners' sugar, and salt in the bowl of a stand mixer fitted with a paddle attachment. Mix on low speed until combined, about 15 seconds. Add butter and beat on low speed until a dough forms and pulls away from the sides of the mixer, about 12 minutes. Transfer dough to a parchment-lined work surface.

  2. Using your hands, form the dough into a ball and flatten slightly. Lay a second sheet of parchment on top. Using a rolling pin, roll dough to an even layer about 3/16th of an inch thick.

    Rolling short bread dough between two layers of parchment paper.
  3. Cut out as many circles as you can using a 2 1/2-inch round cookie cutter. Cut a second circle out of the center of half of them using a 2 1/4-inch cookie cutter.

    Cutting out cookie rounds in two concentric circles, one larger than the other.
  4. Transfer the whole circles to a parchment-lined baking sheet with a thin metal spatula (there should be room for about 24 circles on the sheet). Top each circle of dough with one of the punched-out rings of dough, pressing down slightly to adhere. Prick the center of each cookie 4 times with a toothpick or wooden skewer to dock. Gather any dough scraps and repeat rolling, cutting and transferring process until 24 full cookies are formed. Discard or reserve remaining dough for another use.

    Baked short bread cookie base for homemade Twix.
  5. Bake cookies for 10 minutes, then reduce oven temperature to 300°F (150°C) and continue baking until cookies are pale golden brown around the edges, about 15 minutes longer, rotating pan halfway through cooking. Remove from oven, transfer to a wire rack set in a parchment-lined rimmed baking sheet, and set aside to cool.

  6. For the Caramel: Combine condensed milk, butter, both sugars, corn syrup, salt, and water in a medium saucepan. Bring to a boil, stirring constantly with a heat-resistant rubber spatula or spoon. When mixture reaches 245°F (118°C) on an instant-read thermometer, stir in vanilla, immediately remove from heat, and transfer mixture to a 2-cup liquid measure.

    Caramel bubbling in a saucepan on the stove.
  7. Carefully spoon caramel into the center of each cookie, letting it rise slightly above the lip of the shortbread ring. Excess caramel can be poured into a lightly buttered baking dish, cooled completely at room temperature, turned out of dish, and cut into individual caramel candies.

    Filling the short bread cookie base with caramel sauce.
  8. For the Chocolate: Allow caramel to cool while you prepare the chocolate. Remove 1/4 cup of chocolate and set aside. Place remaining chocolate in a microwave-safe container and microwave in 15-second intervals, stirring after each one, until chocolate is completely melted and registers 115°F (46°C) on an instant-read thermometer (do not overheat). Add half of reserved chocolate to bowl and stir vigorously with a rubber spatula. Continue stirring and adding reserved chocolate a bit at a time until temperature drops to between 84 and 86°F (28 and 30°C). Return to microwave and microwave at 10-second intervals, stirring vigorously in between, until chocolate registers 90°F (32°C). Be careful not to heat past 94°F (34°C). (If chocolate heats past 94°F, reheat to 115°F and repeat this step. See here for instructions on how to temper chocolate using a sous-vide cooker or a food processor with a hair dryer.)

    Combining chocolate with melted chocolate to temper the chocolate.
  9. Pour or spoon melted chocolate over cookies, letting excess drip through cooling rack. Set aside for 1 minute, then sprinkle a small amount of coarse sea salt on the center of each cookie. Let chocolate harden to room temperature for 10 minutes, transfer to refrigerator for 10 minutes, then remove cookies from wire rack using a thin metal spatula. Store in a covered container at room temperature for up to 5 days.

    Sprinkling salt on homemade Twix.

Special Equipment

Stand mixer, thermometer, blender or spice grinder, rolling pin, 2 1/2- and 2 1/4-inch round cookie cutters

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Nutrition Facts (per serving)
273 Calories
16g Fat
28g Carbs
4g Protein
Show Full Nutrition Label Hide Full Nutrition Label
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Nutrition Facts
Servings: 24
Amount per serving
Calories 273
% Daily Value*
Total Fat 16g 21%
Saturated Fat 10g 50%
Cholesterol 21mg 7%
Sodium 154mg 7%
Total Carbohydrate 28g 10%
Dietary Fiber 3g 11%
Total Sugars 16g
Protein 4g
Vitamin C 0mg 1%
Calcium 45mg 3%
Iron 3mg 18%
Potassium 185mg 4%
*The % Daily Value (DV) tells you how much a nutrient in a food serving contributes to a daily diet. 2,000 calories a day is used for general nutrition advice.
(Nutrition information is calculated using an ingredient database and should be considered an estimate.)