Preheat your oven to 350°F (175°C). Grease and flour two 9-inch round cake pans.

In a large mixing bowl, whisk together the flour, cocoa powder, baking powder, and salt.

In another bowl, mix the brown sugar, olive oil, and eggs until well combined.

Gradually add the dry ingredients to the wet ingredients, alternating with water or coffee. Stir in the vanilla extract.

Pour the batter into the prepared cake pans and bake for 25-30 minutes, or until a toothpick inserted in the center comes out clean. Let cool in the pans for a few minutes before transferring to a wire rack.

For the syrup, combine the white sugar and water in a saucepan, bring to a boil, then remove from heat. Stir in brandy or cognac and let cool.

For the mousse, melt the dark chocolate in a heatproof bowl over simmering water. Remove from heat and let cool slightly.

In a separate bowl, whip the heavy cream until soft peaks form. Gently fold in the melted chocolate, honey or maple syrup, and additional cocoa powder until just combined.

To assemble, layer the cake. Drizzle some syrup over the cake layers before adding mousse. Refrigerate until set. Serve chilled and enjoy!