1-First Step: Prepare the Cake Layers: Preheat your oven to 350°F and grease your pans, then line them with parchment paper for easy removal. Sift together the dry ingredients: 2 1/4 cups all-purpose flour, 1 cup unsweetened cocoa powder, 1/2 cup black cocoa powder, 1 1/2 teaspoons salt, 2 1/4 teaspoons baking soda, and 1 teaspoon baking powder. This ensures everything mixes evenly and avoids lumps. In a separate bowl, cream 1 1/2 cups unsalted butter and 2 1/4 cups granulated sugar until it’s pale and fluffy that takes about 3-5 minutes. Beat in 4 large eggs one at a time, then mix in 1 1/2 tablespoons pure vanilla extract and 1 1/2 tablespoons instant coffee granules, followed by 3/4 cup sour cream. Alternate adding the dry ingredients and 2 1/4 cups buttermilk, mixing until just combined. Divide the batter into 6 portions and bake for 18-20 minutes. Let the layers cool completely, then chill them in the refrigerator for easier handling about 1 hour works great.

2-Second Step: Make the Chocolate Mousse Filling: Heat 1/4 cup of the heavy cream until it’s simmering, then pour it over 4 oz chopped dark or semisweet chocolate. Stir until smooth and let it cool completely. In another bowl, whip the remaining 1/2 cup heavy cream with 2 tablespoons powdered sugar until stiff peaks form. Fold the whipped cream into the cooled chocolate mixture gently. Chill this mousse in the fridge until it’s set, which might take around 1-2 hours. You’ll know it’s ready when it’s spreadable but not too firm.

3-Third Step: Prepare the Chocolate Ganache: Heat 1 1/2 cups heavy cream until simmering, then pour it over 16 oz chopped semisweet or dark chocolate and 1/4 cup unsalted butter. Stir everything until it’s smooth and glossy. Pop it in the fridge, stirring every 20 minutes until it thickens to a spreadable consistency about 1-2 hours total.

4-Fourth Step: Assemble the Cake: Spread a bit of ganache on your cake board to hold the first layer in place. Alternate the six cake layers with ganache and mousse, stacking them carefully. Once assembled, chill the cake for about 30 minutes to set. Frost the top and side with the remaining ganache, then press 4 cups mini chocolate chips onto the side right away. Top it off with 4-6 halved chocolate squares for a polished look. Let the whole cake chill for another hour to firm up.

5-Final Step: Serve and Enjoy: Slice your cake and serve it at room temperature for the best flavor warm it slightly if needed. This six layer wonder serves 12-16 people and pairs great with coffee or ice cream. Remember, total time is about 6 hours and 5 minutes, so plan ahead for the best results.