Crust: Preheat the oven to 350 degrees F. In a bowl, mix the ingredients together. Thickly butter a 9 or 10-inch springform pan and press the mixture into the bottom of the pan. Refrigerate, uncovered, while you make the filling.;
Filling: In a mixer fitted with a whisk attachment (or using a hand mixer), mix the ricotta, sour cream, egg yolks, and flour until smooth (the mixture will remain a bit grainy from the ricotta). Add the sugar, lemon juice, and vanilla and blend until creamy. Fold in the raisins.
In a clean dry bowl, whip the egg whites until stiff but not dry. Fold them into the filling mixture. Pour into the prepared pan and bake until the top of the cake is set and dry to the touch, though still a bit soft in the center, 70 to 80 minutes. It should "shimmy" a bit when you shake the pan; it will firm up more as it cools. Let cool in the pan. The cake will deflate a bit as it cools. Cover and refrigerate the cake at least 2 hours. (Or refrigerate until ready to serve, up to 48 hours.) Remove the sides of the pan and serve cold.
Recipe courtesy of Gale Gand, "Butter Sugar Flour Eggs" by Gale Gand, Rick Tramonto, Julia Moskin: Clarkson N. Potter Publishers, 1999