1. Preheat oven to 350 F.
2. Lightly grease 20 cm cake pan and line the base. Beat together the butter and sugar until light and fluffy. Gradually add the eggs, beating well after each addition.
3. Sieve the flour, baking powder and cocoa powder together and fold into the mixture along with the ground almonds. Pour into the prepared pan and bake for 25 minutes or until springy to the touch. Leave to cool completely. Wash and dry the pan and return the cooled cake to the pan.
4. Topping:
5. Heat the chocolate, butter and cream in a heavy based pan and stir until smooth. Cool, and then chill for 30 minutes. Beat well with a wooden spoon and chill for a further 30 minutes. Beat the mixture again, and then add the cake crumbs, beating until well combined. Spoon over the sponge base .Arrange the truffles over the mixture and press slightly .Sift some cocoa powder over the truffles in a decorative way. Chill.