• Begin by preheating your oven to 325°F (163°C). Grease and flour three 8-inch round cake pans, lining the bottoms with parchment paper if desired for easier release.
• In a mixing bowl, combine the Devil’s Food cake mix, flour, sugar, and dry pudding mix, stirring to ensure all dry ingredients are evenly distributed.
• Add sour cream, vegetable oil, water, eggs, and vanilla extract to the bowl. Start mixing at a low speed for 30 seconds, then increase to medium speed for 2 minutes, stopping to scrape the bowl as needed. The batter should be smooth and well-blended.
• Divide the batter evenly among the prepared cake pans. Bake for 20-25 minutes, checking for doneness by lightly pressing the top to see if it springs back or inserting a toothpick that comes out with a few moist crumbs. Remember that dark pans may reduce the baking time slightly.
• Once done, let the cakes cool in their pans on a wire rack for about 10 minutes, then carefully turn them out to cool completely before frosting.

Chocolate Mousse Filling

• In a bowl, combine the sifted chocolate pudding mix with the heavy cream. Using a handheld mixer on low speed, mix until the pudding is fully incorporated. Then increase the speed to high, whipping until the mousse is thick and fluffy. Adjust with more heavy cream if needed to achieve a spreadable texture. If you prefer, you can whisk by hand until thickened. Chill until ready to use.

Chocolate Buttercream

• In a mixing bowl, cream the softened butter on low to medium speed until smooth. Add the vanilla extract, powdered sugar, salt, and sifted cocoa powder, mixing slowly to incorporate.
• Add the milk gradually, adjusting for desired consistency as you blend. Continue mixing for 5-6 minutes until the frosting becomes light and smooth. If it’s too thick, add small amounts of milk; if too soft, add powdered sugar.

Assembling and Decorating the Cake

• Place one cake layer on a serving plate or cake pedestal. Spread a generous layer of chocolate mousse on top. If the mousse is thinner, you may want to pipe a dam of buttercream around the edge to contain the filling.
• Add the second layer and repeat the process with the mousse. Place the third layer on top, ensuring any gaps between layers are filled with buttercream.
• Apply a thin crumb coat of buttercream to the top and sides of the cake. Chill in the freezer for 15 minutes or refrigerate longer to set. Once firm, apply a final layer of buttercream.
• Use an offset spatula to create textured swirls or smooth the surface as desired. For a finishing touch, pipe rosettes or stars around the top edge with a 1M piping tip. Enjoy the finished cake as a decadent centerpiece for any celebration.