For the pasta frolla, combine the dry ingredients and mix well. Rub in the butter until it is absorbed, making sure the mixture remains cool and powdery and does not become pasty. Beat the egg with the milk or water and stir in with a fork. Continue stirring until the dough holds together, then knead it briefly, just until smooth. Shape into a disk, wrap in plastic, and refrigerate at least 1 hour, or until firm.
For the ricotta filling, press the ricotta through a fine sieve into a mixing bowl or puree it in a food processor fitted with the metal blade. Stir in the sugar, then the egg whites, one at a time. Stir in the remaining filling ingredients.
Roll the reserved dough into a 9-inch disk. Place the disk of dough on top of the filling and loosen the top edge of the bottom crust from the side of the pan with a thin knife. Fold the edge of the bottom crust over the top crust.
Bake at 350 degrees for about 45 minutes, until the filling is set and the pastry is a light gold. Cool in the pan before unmolding. To unmold, invert onto a platter and lift off the pan. Dust with the confectioners’ sugar just before serving. Serve the cassata at room temperature.
Confectioners’ sugar for finishing
© 1990 Nick Malgieri. All rights reserved.