Yields about 16 cupcakes
1/4 cup (1/2 stick) unsalted butter, room temperature
1 cup granulated sugar
2 large eggs
1/3 cup sour cream (or plain, non-fat yogurt)
1/4 cup vegetable oil
2 tablespoons vanilla extract
1 3/4 cups cake flour
1 1/2 teaspoons baking powder
1/2 teaspoon baking soda
1/2 teaspoon salt
2/3 cup milk
Preheat oven to 350 degrees F (180 degrees C). Line a cupcake pan with baking cups.
In a large mixing bowl, cream together the butter and sugar until light and fluffy. Add the eggs one at a time, beating well after each addition. Beat in the sour cream, vegetable oil, and vanilla extract. Gradually add in the cake flour, baking powder, baking soda, and salt.
Stir in the milk, mixing until batter is uniform and smooth.
Fill baking cups about 2/3 full (or a little less) and bake for 12-14 minutes, or until a toothpick inserted into the center comes out clean.
Remove from the oven, transfer cupcakes to a cooling rack, and allow to cool to room temperature before frosting or serving.