1. Preheat oven to 350°F. Press 12 cookies evenly into bottom of 9x9-inch baking pan lightly sprayed with cooking spray.
2. Combine sour cream, sugar, egg yolks and cornstarch in saucepan. Cook over medium heat, stirring occasionally, until mixture comes to a boil. Gently boil and stir for 1 minute.
3. Spread filling over pressed cookies. Break apart remaining cookies and place evenly over mixture. Bake for 25-30 minutes or until golden brown. Cool completely; cut into bars.
Tip: For the raisin lovers, try adding extra raisins to the custard filling.