Make the Chocolate Frosting (in advance)
- Place chopped chocolate into a large heatproof bowl.
- In a medium saucepan, combine heavy cream and butter. Cook on med-high, stirring often, until just simmering.
- Pour hot cream over chopped chocolate and cover bowl with plastic wrap. Let sit 5 minutes.
- Stir gently until completely smooth.
- Place plastic wrap directly on top of chocolate. Allow to thicken and set overnight.*
Make the Chocolate Cake:
- Preheat oven to 350F. Grease two 8″ cake rounds, dust with cocoa powder and line bottoms with parchment.
- Place flour, sugar, cocoa powder, baking soda, baking powder and salt into the bowl of a stand mixer. Mix until well combined.
- In a medium bowl, whisk eggs, oil, buttermilk, and vanilla. Very slowly pour in hot water while whisking constantly.
- Add wet ingredients to dry and mix on medium for 2 to 3 minutes. Batter will be very thin.
- Pour batter evenly into prepared pans. Bake for approximately 30 minutes or until a toothpick inserted into the center comes out mostly clean.
- Place cakes on wire rack to cool for 10 minutes then turn out onto wire rack to cool completely.
- Once cooled, cut each layer in half horizontally, if desired.
Assemble the Cake:
- Place one layer of cake onto a cake stand or serving plate. Top with a thin layer of chocolate frosting (approximately 2/3 cup). Spread evenly.
- Repeat with remaining layers of cake and frosting. Crumb coat the cake. Chill for 30 minutes.
- Frost the cake and smooth the sides and top, reserving a small amount of chocolate frosting for the top decorations, if desired. Place cake back in the fridge for 20 minutes to set.
- Place a bowl upside-down on a baking sheet. Place cake on inverted bowl so that the sides hang over.
- Gently press chocolate flakes (or chocolate sprinkles) into the sides and top.
- Pipe dollops of reserved chocolate frosting on top using a large open star tip, like a Wilton 6B, if desired.