Instructions

• Preheat the oven to 350°F (180°C). Grease three 8-inch cake pans with cooking spray (line bottoms with parchment if you like) and set aside.
• Measure and set aside 1 cup of the 3 cups chopped chocolate for the cookie dough. Put the remaining chopped chocolate and 3/4 cup plus 2 tablespoons coconut oil in a microwave-safe bowl.
• Melt the chocolate and coconut oil in the microwave in 20-second intervals, stirring between intervals, until smooth and fully combined.
• Whisk 2 1/4 cups sugar into the melted chocolate mixture until combined.
• Add the 6 large eggs one at a time, whisking well after each addition until the mixture is smooth.
• Whisk in 6 tablespoons cocoa powder and 9 tablespoons cornstarch until the batter is smooth and uniform.
• Divide the batter evenly among the three prepared pans and smooth the tops. Bake for 23–25 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs.
• Let the cakes cool in their pans for 10–15 minutes, then run a knife around the edges and transfer the layers to a wire rack to cool completely.
• While the cakes cool, heat-treat the 2 cups all-purpose flour for the cookie dough: spread the flour in an even layer on a baking sheet and bake in the oven for about 5–7 minutes (allow to cool completely). (Use this cooled, heat-treated flour in the cookie dough.)
• Make the edible cookie dough: in a stand mixer or with a hand mixer, cream together 1 cup butter, 1 cup light brown sugar, and 1/3 cup sugar until combined and slightly fluffy. Add 2 teaspoons vanilla extract and 2 tablespoons milk and mix until incorporated.
• With the mixer on low, slowly add the cooled, heat-treated 2 cups all-purpose flour and mix just until combined. Fold the reserved 1 cup chopped chocolate into the dough with a spatula.
• Assemble the cake: place one cooled cake layer on your serving plate. Spread a thin layer of the 1 cup chocolate frosting over the layer, then spread half of the cookie dough evenly on top of the frosting.
• Place the second cake layer on top, repeat with a thin layer of frosting and the remaining half of the cookie dough. Top with the final cake layer.
• Spread any remaining chocolate frosting on top of the cake (and on the sides, if desired).
• Refrigerate the assembled cake for at least 1 hour to firm up before slicing. Store leftovers refrigerated.