1️⃣ Make the Chocolate Cake Base

1. Preheat oven to 350°F (175°C). Grease and line a 9-inch springform pan with parchment paper.
2. In a bowl, whisk flour, cocoa powder, baking soda, and salt.
3. In another bowl, beat butter, granulated sugar, and brown sugar until fluffy (2 minutes).
4. Mix in eggs one at a time, followed by vanilla extract.
5. Alternately mix in flour mixture and buttermilk, then stir in hot coffee/water until smooth.
6. Pour batter into the pan and bake for 20-25 minutes. Cool completely.

2️⃣ Prepare the Chocolate Mousse

1. In a saucepan, melt chocolate chips and butter over low heat, stirring until smooth.
2. Remove from heat and stir in vanilla extract. Let cool slightly.
3. In a separate bowl, whip heavy cream until soft peaks form.
4. Gently fold the whipped cream into the chocolate mixture until smooth.

3️⃣ Assemble the Cake

1. Spread the chocolate mousse evenly over the cooled cake layer.
2. Refrigerate for 1-2 hours to set.

4️⃣ Make the Ganache Topping

1. Heat heavy cream until warm (not boiling), then pour over chocolate chips.
2. Let sit for 1 minute, then stir until smooth. Add butter for a glossy finish.
3. Let the ganache cool slightly, then pour over the mousse layer.

5️⃣ Chill & Serve

• Refrigerate for at least 3 hours (or overnight) before slicing.
• Serve chilled with whipped cream, chocolate shavings, or berries.