Sourdough Chocolate Mousse Cake

For the Cake
1. Preheat the oven to 180°C (350°F).
2. In a bowl, whisk together the flour, cocoa powder, sugar, baking soda, baking powder, and salt. Set aside.
3. In the bowl of a stand mixer, mix the sourdough starter and milk until the starter is fully dissolved. Add the oil, egg, and vanilla, and mix until fully combined.
4. On very low speed, add the dry ingredients and mix just until no lumps remain. Prepare two round cake pans by greasing and lightly flouring them. Divide the batter evenly between the pans. Bake for 20–25 minutes, or until a toothpick inserted in the centre comes out clean.
(If you only have one 6- to 8-inch pan, adjust the baking time to about 40 minutes.)
Let cool at room temperature, then refrigerate. This step can be done ahead of time to save time.

For the Chocolate Mousse
5. In a bowl, heat the 330 g of cream in the microwave until just boiling. Pour the hot cream over the semi-sweet chocolate chips and let sit for 3 minutes. Stir until smooth. Cover and refrigerate for about 2 hours, until completely chilled. It’s very important that the ganache is fully cold—if it’s still warm, it won’t whip properly.
6. Once fully chilled, whip the ganache for about 2 minutes until it becomes mousse-like. Add the additional 100 g of whipping cream to lighten the texture and whip for another minute until fully incorporated. Cover and refrigerate until ready to assemble.

To Assemble the Cake
7. Slice each cake layer in half to create 4 layers total. Place the first layer on your serving plate and spread a generous amount of mousse on top. Repeat with the remaining layers. Cover the entire cake with the remaining mousse.
Refrigerate for 15 minutes while you prepare the glossy ganache.

For the Glossy Ganache
8. In the microwave, bring the 140 g of cream just to a boil. Pour the hot cream over the chopped dark chocolate and let sit for 3 minutes.
9. Whisk by hand until smooth and glossy.
10. Gently pour the ganache over the cake, making sure to cover the entire surface. I recommend placing your cake on a cooling rack with a plate or tray underneath. The excess ganache will drip through the rack and collect on the plate instead of your counter. Don’t worry if it’s not perfect—everything is made with love.
11. Decorate the sides of the cake with sliced almonds, chocolate chips or shavings, pistachios, or whatever you have on hand, before the ganache sets.
12. Refrigerate until ready to serve, then enjoy every bite with the people you love.