Try this easy s'mores tart recipe from Claire Saffitz

Claire Saffitz made her mark in the confections space even before her hit debut book "Dessert Person" amplified her into a trusted household name for all things sweet.

In her follow-up title, "What's for Dessert: Simple Recipes for Dessert People: A Baking Book," Saffitz shares even more on the topic she knows best.

The author, chef and YouTube personality joined "Good Morning America" to offer up a delicious new dessert just in time for the holidays.

S'mores Tart

"S'mores desserts are typically a little maximalist for my taste. But over the past couple of years I've been lucky to spend a portion of my time in the Hudson Valley, about ninety minutes outside of New York City, where, thanks to the regular occurrence of indoor and outdoor fires, I rediscovered my childhood love of classic s'mores. It got me brainstorming ways to translate s'mores into a more refined dessert, and since nothing is more refined than a chocolate tart, that became my starting point. The filling is a basic ganache lightened with whipped cream to give it a mousse-like texture (a genius technique I learned from Dorie Greenspan, who uses it for the topping of her chocolate Lisbon Chocolate Cake). It's set inside a thick graham cracker crust and topped with my homemade marshmallow (note that you should wait to prepare the marshmallow topping until after you've filled the tart)."

Serves: 8
Difficulty: 2 (Easy)
Active time: 55 minutes (does not include making the marshmallow)
Total time: 3 hours 30 minutes

Ingredients
9 tablespoons unsalted butter (4 1/2 ounces / 128 grams), divided
7 ounces (198 grams) graham crackers (about 13 sheets)
1 large egg yolk (1/2 ounce / 15 grams)
2 tablespoons plus 3/4 cup sugar (6.2 ounces / 175 grams)
1/2 teaspoon Diamond Crystal kosher salt or 1/4 teaspoon Morton kosher salt, plus several pinches
6 ounces (170 grams) semisweet chocolate (64-70% cacao), finely chopped
1 1/4 cups heavy cream (10.6 ounces / 300 grams), chilled, divided
Easy Marshmallows (recipe to follow below)

Directions

The oven: Arrange an oven rack in the center position and preheat the oven to 350 F.

Make the crust: Melt 5 tablespoons (2 1/2 ounces / 71 grams) of the butter and set aside to cool. Place the graham crackers in a resealable bag, press out the air, and seal. Use a rolling pin or a heavy-bottomed saucepan to crush the crackers, periodically shaking the bag so the larger pieces settle to one side, and continue to crush until you have very fine, uniform crumbs (you can also pulse the graham crackers in a food processor until finely ground, but it's very doable by hand). Transfer the crumbs to a medium bowl and add the egg yolk, 2 tablespoons sugar, 1/2 teaspoon salt, and the melted butter. Toss with a fork to combine then rub the mixture between your fingers until it looks like wet sand.

Press in the crust and bake: Transfer just shy of half the mixture to a 9-inch removable-bottom tart pan and scatter the crumbs evenly around the perimeter. Use a straight-sided glass or 1-cup dry measure to press the mixture firmly against the fluted sides (it will form a thick layer), then scatter the remaining crumbs across the bottom of the pan and use the bottom of the glass or measuring cup to flatten the mixture into an even layer. Place the tart pan on a sheet pan and bake until the crust is fragrant, firm to the touch, and dark brown around the edges, 13 to 18 minutes. Remove from the oven and let cool completely.

Make the ganache: In a large heatproof bowl, combine the chocolate and a generous pinch of salt and set aside. In a small saucepan, heat 3/4 cup (6.3 ounces / 180 grams) of the cream over medium heat just until you see gentle bubbling around the sides. Remove the saucepan from the heat and set it aside for 30 seconds to cool slightly, then pour it over the chocolate. Cut the remaining 4 tablespoons (2 ounces / 57 grams) butter into 1/2-inch pieces and add them to the bowl. Let the chocolate mixture sit undisturbed for about 5 minutes to allow the chocolate to melt. Whisk the ganache gently, starting in the center of the bowl and working outward, until the mixture is completely smooth. Set the bowl aside while you whip the cream.

Potential pitfall: Make sure you allow the cream to cool slightly before pouring it over the chocolate. Ganache is temperature-sensitive and will "break" if it gets too hot, meaning that the cocoa butter will separate from the solids and make the mixture look oily. If it does break, whisk in 2 tablespoons water to bring it back together.

Whip the remaining cream: In a medium bowl, with a hand mixer, whip the remaining 1/2 cup (4.2 ounces / 120 grams) cream on low speed and gradually increase the speed to medium-high as it thickens until you have medium peaks (see Whipping Cream, page 355). Set the bowl aside.

Whip the ganache: Beat the ganache with the hand mixer (no need to wash after whipping the cream) on low speed to start and gradually increase the speed to medium-high until the ganache thickens to the consistency of chocolate pudding and holds the marks of the whisk, about 4 minutes. Scrape in the whipped cream and fold until the mixture is streak-free (for more on the proper technique, see Folding a Mixture, page 351). Scrape the whipped ganache into the cooled tart crust and smooth the surface, working it to the sides in an even layer. Set the tart aside, uncovered at room temperature, until the filling is set, at least 15 minutes.

Top with the marshmallow: Follow the recipe for the marshmallows, but rather than transferring the mixture to a pastry bag, scrape it onto the tart and swirl with the back of a spoon across the surface. Let the tart sit uncovered at cool room temperature until the marshmallow is firm and set, at least 2 hours. If desired, brown the surface of the marshmallow with a kitchen torch. Press up on the bottom of the tart pan to pop the tart out of the fluted ring and place it on a serving plate.

Easy Marshmallows

Essential technique: Softening gelatin

Sprinkle the gelatin with cold water: Fill a small, shallow bowl with 1/4 cup (2 ounces / 57 grams) of cold tap water and slowly sprinkle the gelatin across the surface so the granules separate as they fall into the bowl [A]. Do not stir the mixture. Using cold water ensures that the granules hydrate slowly and evenly.

Let the gelatin hydrate: Let the gelatin sit until the granules have absorbed the water, look swollen and translucent, and the mixture is solid and bouncy to the touch, 5 to 10 minutes. Hydrating the gelatin, also known as "blooming," is required so it can melt fully and evenly into the recipe.

Essential technique: Setting up a double boiler

Simmer water in a saucepan: Fill a medium saucepan with about 1 inch of water and bring to a simmer over medium-low heat, then reduce the heat to low. You want the water to be steaming and barely bubbling, if at all.

Place a bowl over top: Rest a medium heatproof bowl, preferably metal, on top of the saucepan [B]. The bottom of the bowl should sit stably inside without touching the water, while the sides should extend several inches beyond the rim of the saucepan so you can lift it off easily (be careful, the bowl will quickly heat up). This setup, which mimics a piece of cookware called a double boiler, uses the steam inside the saucepan to gently warm the contents of the bowl.

Melt the gelatin: Scrape the softened gelatin into the bowl of the double boiler [C] and stir with a flexible spatula until it's completely melted and translucent with no sign of any granules, 1 to 2 minutes.

Potential pitfall: If the gelatin isn't completely melted, the marshmallow mixture won't fully set and will deflate as it sits. Make sure you examine the melted gelatin closely to confirm it's granule-free.

Add the sugar and the egg whites and heat until dissolved: Carefully remove the bowl from the saucepan, place it on the work surface, and let it cool for a minute. Add the sugar, corn syrup, egg whites, cream of tartar, and a generous pinch of salt and whisk to combine. Place the bowl back over the saucepan and whisk continuously until the sugar is dissolved and the egg white mixture has a sticky, syrupy consistency, about 5 minutes (rub a dab between your fingers -- it should feel grit-free). If you are concerned about consuming unpasteurized egg whites, continue to whisk the mixture constantly over the double boiler until it registers 160 F on an instant-read thermometer, which will take several minutes longer.

Beat the marshmallow mixture: Carefully remove the bowl from the saucepan. Use a hand mixer to beat the mixture, starting on medium-low and gradually increasing to high, until you have a very thick, dense, and glossy meringue-like mixture that holds a stiff peak, 7 to 9 minutes. Beat in the vanilla. If making the S'mores Tart (page 257), proceed to the recipe. If making individual marshmallows, set the bowl aside and proceed to step 8.

Essential technique: Filling a pastry bag

Fold over the bag: Place a pastry bag or resealable plastic bag inside a tall and narrow 1-quart container or large, tall glass and fold down the top of the bag around the outside of the container or glass (this will help keep the sides of the bag clean).

Fill the bag: Use a flexible spatula to scrape about one-third of the mixture into the bag and push it down toward the bottom. Scrape in the remaining mixture, taking care not to form big air pockets, which would make it more difficult to pipe [G].

Seal: Lift up the sides of the bag to unfold them and pull the bag out of the container. Then, pinning the top of the bag to the work surface and starting at that end, drag the edge of a bench scraper or other straightedge firmly down the length of the bag to force the mixture toward the point or corner. Gather the ends of the bag and twist to seal. Set the bag aside.

Pipe the marshmallows and let set: Line a sheet pan with a silicone baking mat or parchment paper and use a fine-mesh sieve to dust the entire surface generously and evenly with a layer of confectioners' sugar. Snip a 1-inch opening in the tip or corner of the bag and pipe ping-pong-sized dollops of the marshmallow mixture onto the prepared sheet pan, piping until you've used the entire mixture. If you prefer a looser look, you could spoon free-form blobs of marshmallow onto the sheet pan. Set the pan in a cool spot and let the marshmallows sit uncovered until they are set, about 4 hours.