S'mores Cake

Gather all ingredients.

Preheat the oven to 350 degrees F (175 degrees C). Line the bottom of two 9-inch cake pans with parchment paper, lightly spray with baking spray. (5 minutes)

Combine cake mix, eggs, milk, and butter in a large bowl. Beat with an electric mixer until well combined. Mix in espresso powder and 2 teaspoons vanilla extract. Divide batter evenly between prepared pans, spreading into even layers. (10 minutes)

Bake in the preheated oven until a toothpick inserted into the center of cakes comes out clean, 25 to 30 minutes. Cool cakes in pans on a wire rack for 20 minutes, then remove cakes from pans and let cool completely on a wire rack. (50 minutes)

While cakes are baking, place chocolate chips into a heatproof bowl. Bring cream in a small saucepan to a gentle simmer over medium-low heat, stirring constantly, about 6 minutes. Pour hot cream over chocolate chips and let stand for 5 minutes. Gently stir together in a circular motion to evenly blend chocolate into cream, without adding a lot of air. Let chocolate mixture cool, uncovered, at room temperature, stirring occasionally, until thickened to a spreadable consistency, about 1 ½ hours. (100 minutes)

Meanwhile, bring a small saucepan filled with 2 inches water to a simmer over medium-low heat. Beat egg whites, sugar, and cream of tartar together in a work bowl of a stand mixer fitted with a whisk attachment on medium speed until well combined, about 1 minute.

Place mixer bowl over simmering saucepan, ensuring the bottom of the mixing bowl does not touch the water. Cook egg white mixture, whisking constantly, until a candy thermometer reaches 160 degrees F (70 degrees C) and the sugar crystals have dissolved, 8 to 10 minutes.

Remove bowl from heat, and return to stand mixer. Beat on high speed, gradually adding remaining 1 teaspoon vanilla. Beat until stiff peaks form, 6 to 7 minutes.

Set aside 2 cups of marshmallow cream. Place remaining marshmallow cream into a piping bag fitted with a large star tip.

Remove cooled cakes from pans and discard parchment. Using a serrated knife, trim the tops of the cooled cakes to create a level top; use excess cake for trifle or just eat.

Place 1 cake layer on a cake stand or plate, cut-side up. Spread reserved 2 cups marshmallow cream in an even layer on cake top.

Sprinkle 1/2 cup of the graham cracker crumbs evenly over top.

Top with remaining cake layer, cut-side down. Fill in any empty spots in seams of cake layers using marshmallow cream in piping bag; smooth sides using an offset spatula. Refrigerate stacked cake, uncovered, for 30 minutes.

Spoon 1 ¼ cups cooled chocolate mixture over top of the stacked cake. Spread into an even layer using a large cake spatula, allowing excess to extend over the sides. Frost sides of cake using remaining chocolate mixture, smoothing into an even layer.

Using marshmallow cream in piping bag, pipe 10 large rosettes along the top, outside edge of the cake.

Sprinkle center of the cake with remaining 1/4 cup graham cracker crumbs.

Arrange graham cracker rectangles upright on the long sides of each rectangle in a spoke-wheel design inside rosette rings on top of cake. Pipe 1 large rosette in center of graham cracker spoke-wheel design. Refrigerate, uncovered, until ready to serve, at least 30 minutes or up to 48 hours.

Just before serving, use a kitchen torch to slightly brown marshmallow rosettes. Slice and serve cake.