Pre-heat the oven to 325°F (170°C) and grease a medium-sized spring form. Mine was heart shaped but you can pretty much use any tin with around a 18-24cm diameter, although baking times will need to be adjusted accordingly.
For the cake: heat the butter and chocolate in a pan until just melted. Remove from the heat and add the brewed coffee. Set to one side to cool.
In a food processor (or using a whisk) beat the eggs and brown sugar together for about 30 seconds. Add the cooled chocolate mixture and stir together, just until everything is well combined.
Add the flour, cocoa and vanilla sugar and once again, just stir until everything is well mixed. Pour the batter into the tin and then bake for around 18-20 minutes, just until the middle is firm. Remove from the oven and allow to cool completely.
For the mousse: melt the chocolate in a Bain Marie (double-boiler) and then set to one side to cool a little.
In a bowl, whip the cream until it starts to form peaks. Carefully fold in the chocolate, making sure there are no streaks. Pour over the cold cake and then level of the top. Cover with cling-film and place in the fridge for at least four hours to firm up.
When ready to serve, decorate with almonds and strawberries. Enjoy!