* 4 cups fresh or frozen blackberries, drained, divided
* Whipped cream
* In a small bowl, combine the flour, sugar and baking powder; cut in butter until crumbly. Stir in egg until dough forms a ball. Press onto the bottom and 2 in. up the sides of an ungreased 9-in. springform pan.
* For filling, beat the egg yolks, sour cream, sugar and vanilla in another small bowl just until combined. Sprinkle 2 cups blackberries over crust. Carefully pour sour cream mixture over berries. Place pan on a baking sheet.
* Bake at 325° for 1-1/2 hours or until center is almost set. Cool on a wire rack (center will fall).
* Remove sides of pan. Top with whipped cream and remaining blackberries. Refrigerate any leftovers. Yield: 12-14 servings.
Editor's Note: Even a tight-fitting springform pan may leak. To prevent drips, place the pan on a shallow baking pan in the oven.