Preheat the oven to 400 degrees F. Grease two square cake pans. In a small saucepan over medium-low heat, combine the beer, butter and cocoa powder, and stir until the butter melts.
In a large bowl, combine the flour, sugar, baking powder and salt.
In another bowl, beat the eggs and creme fraiche. Add the beer mixture to the egg mixture and mix. Then add dry ingredients into the wet ingredients and mix. Pour the batter into the prepared cake pans and bake until a toothpick inserted in the center comes out clean, 45 minutes.
Cool the cakes to room temperature.
Brush the top of the cakes with beer. Spread the ganache on one of the cakes, and place the second cake on top. Then top the second cake with ganache. Slice the cake and serve each piece with roasted chestnuts, salted caramel and some beer-poached pears.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.