Using the prongs of a fork, mix the Ricotta with sugar and a little Maraschino or other clear liqueur and then sieve. Add to half of this cream, small pieces of dark chocolate and diced candied fruit. Cut the sponge cake in half horizontally, create two cavities inside and stuff with the Ricotta cream. Cover the outside of the dessert with the plain Ricotta cream, smoothing down the surface with a spatula. Garnish to taste with more candied fruit. Leave in the fridge for a few hours before serving.