Double chocolate muffins

Heat oven to 375°F. Place 12 muffin paper liners in a muffin pan.

Put the butter, sugar, and brown sugar into a bowl and beat well. Beat in the eggs, sour cream, and milk until thoroughly mixed. Sift the flour, baking soda, and Cocoa into a separate bowl and stir into the mixture. Add the chocolate chips and mix well.

Spoon mixture into the paper liners. Bake in the oven for 25 to 30 minutes. Remove from the oven and let cool for 10 minutes. Turn out onto a wire rack and let cool completely.