Pumpkin S'mores Cake

Ingredients:

• 165g unsalted butter, room temperature, plus extra for greasing pans
• 6 whole graham crackers
• 2 and 1/4 cups flour
• 2 tablespoons cornstarch
• 2.5 tsp baking powder
• 0.5 tsp of soda
• 1 teaspoon ground cinnamon
• 0.5 tsp salt
• 1 cup granulated sugar
• 3/4 cup light brown sugar
• 4 large eggs, room temperature
• 2 tsp vanilla extract
• 1 can (425 g) canned pumpkin puree
• 0.5 cups of sour milk or kefir
• 110 g dark chocolate, chopped
• 12 marshmallows
• 2 tablespoons cocoa powder
• 1 cup chilled heavy cream
• 0.5 tsp vanilla extract
• Whites of 6 large eggs
• 1 and 1/4 cups granulated sugar
• 1/4 tsp cream of tartar
• A pinch of salt
• 1 tsp vanilla extract

Preparation:

1. Bake the cakes:

   
   Preheat oven to 350°F (175°C). Lightly grease two 9-inch round cake pans and line the bottoms with parchment paper. Process the graham crackers in a food processor until fine crumbs form. Add the flour, cornstarch, baking powder, baking soda, cinnamon, and salt and pulse until evenly distributed.
2. In a large bowl, beat the butter and both sugars with a mixer on medium-high speed until light and fluffy, 3-4 minutes. Beat in the eggs one at a time, beating well after each addition, then beat in the vanilla extract. Reduce the mixer speed to low and beat in the pumpkin puree (the mixture will look curdled). Fold in half the flour mixture, then the buttermilk, then the remaining flour mixture. Divide the batter evenly among the prepared pans. Tap the pans on the counter to release any air bubbles.
3. Bake the cakes until a toothpick inserted into the center comes out clean, 40-45 minutes. Transfer them to a wire rack and let cool for 10 minutes in the pans. Then, loosen the edges with a knife and invert the cakes onto a wire rack; remove the parchment and let cool completely.

4. Meanwhile, prepare the filling:

   
   Melt the chocolate, marshmallows, cocoa powder, and 1/3 cup heavy cream in the microwave in 30-second intervals, stirring occasionally, until smooth. Stir in the vanilla extract. Let cool to room temperature.
5. Whip the remaining 2/3 cup heavy cream in a medium bowl until stiff peaks form. Using a rubber spatula, fold one-third of the whipped cream into the chocolate-marshmallow mixture, then gently fold in the remaining whipped cream. Refrigerate for 1 hour.

6. Meanwhile, prepare the meringue:

   
   In a large heatproof bowl, combine the egg whites, granulated sugar, cream of tartar, and salt. Place over a saucepan of simmering water (the bowl should not touch the water) and heat, whisking, until the mixture is warm and the sugar is completely dissolved, 3-4 minutes. Remove the bowl from the heat. Add the vanilla extract to the whites and beat with a hand mixer on medium speed until the mixture cools and forms stiff, glossy peaks, about 12 minutes (or transfer to a stand mixer and beat for 6-8 minutes).

7. Assemble the cake:

   
   Using a long serrated knife, cut each cake layer in half horizontally, making 4 layers. Place 1 cake layer on a cake stand or plate. Transfer 1 cup meringue to a large zip-lock plastic bag and snip off the corner. Pipe the meringue around the perimeter of the cake (this will prevent the filling from leaking out). Spoon one-third of the chocolate filling inside the ring. Repeat with 2 more layers and top with the final cake layer. Cover the top and sides of the cake with the remaining meringue, spreading it with the back of a spoon to create peaks. Toast the frosting with a blowtorch. Refrigerate the cake for 1 hour before serving.