Mix oatmeal, flour, brown sugar, soda, and melted butter.
Pat ½ of mixture into 9x13-inch pan and bake 15 minutes at 350°F.
Combine yolks, sugar, raisins, sour cream, and cornstarch.**
Boil on low heat for 5-10 minutes, stirring often to avoid scorching.
Pour over baked crust and top with remaining mix.
Bake for 5-10 minutes.
Store in refrigerator if not eating within 3 days.