Start by baking a half recipe of Mamie's chocolate cake in a spring form pan. See recipe in dessert chapter / Mamie's Chocolate Cake. Let the cake cool to room temperature. Trim the crown off the top of the cake so it is level or flat on top. Eat the trim or you may chop it into chunks and fold it into the chocolate mousse. I'd eat it!
To Make Chocolate Mousse:
Bring a small pan of water to a boil, turn off the heat. Place chocolate in a heat safe bowl and allow it to sit over the hot water until the chocolate melts. When the chocolate melts. Fold in soft butter and egg yolks. Then add coffee. The acid in the coffee acts as a flavor magnifier for the chocolate. Remove from heat, reserve.
Beat egg whites and sugar in a small bowl to form soft peaks. Make sure the bowl is clean and fat free, meringue hates fat and oil. Remember when it comes to meringue we need FFE - fat free equipment.
In another bowl, beat heavy cream, sugar and vanilla until soft peaks form.
Mixing the Mousse:
Fold the chocolate into the whipped cream. Then fold the meringue mixture into the chocolate. Pour the mousse into the spring form pan on top of the cake layer, smooth the top with a spatula. Place in the fridge until frozen - about 4 hours to set.
Remove the mousse cake from the spring form pan and cut into slices. Allow to thaw to a good serving texture - about 30-minutes. Plate and garnish with a squiggle of raspberry sauce, whipped cream, a few fresh raspberries and a sprig of mint.
Chocolate Ganache Sauce:
Place one cup chocolate in a bowl, add 1 cup of boiling heavy whipping cream, stir to combine. Pour the chocolate sauce over the mousse cake, mmm!