Old Fashioned Sour Cream Cake Donuts

°Vegetable oil, for frying.

°3 tablespoons softened unsalted butter.

°¼ cup. Granulated sugar.

°¼ cup. Golden brown sugar.

°2 large egg yolks.

°½ tablespoon of vanilla extract.

°1½ cups. Of sour cream.

°2½ cups. All-purpose flour.

°2 tablespoons of baking powder.

°1 tablespoon cornstarch.

°½ tablespoon of salt.

°¼ tablespoon ground nutmeg.

°3 Cups. Of powdered sugar.

°½ Cup. Melted salted butter.

°1 teaspoon of vanilla extract.

°4 tablespoons hot water.