Whisk the ricotta until quite smooth, or blend it in a food processor, then mix in the yoghurt.
Whip the cream and sweeten to taste, then fold this into the ricotta mixture. Spread the mixture over the bottom half of a split sponge cake, then replace the top. The ricotta layer should be a good 3cm thick.
Dust with icing sugar and serve with the berries. Suggest strawberries, raspberries and blackberries.
