Cut the butter into the flour until crumbly. Stir in egg and blend well. Reserve about half cup of the mixture and pat the reamining crumbs lightly into the bottom of a lightly greased 10� springform pan. Beat the ricotta cheese until creamy. Beat in 1 cup of sugar, the flour and the egg yolks one at a time, beating well after each addition. Add the vanilla and candied fruit and blend thoroughly. Beat the egg whites until stiff, adding the remaining sugar gradually. Fold gently into the ricotta mixture. Pour the batter into the prepared pan, sprinkle with reserved crumbs, and bake in a 160ºC oven for about 1 hour 30 minutes, or until firm. Let cool in the pan. Serves 10 to 12. ----