You can call these muffins, or you can call them cupcakes. Whatever you call them, serve them warm from the oven, while the tops are still crisp and the chocolate is meltingly delicious. Or top them with some frosting and watch them disappear!
Preheat the oven to 400 degrees F. Grease 15 to 18 muffin cups or line with paper liners.
In a large mixing bowl, sift together the flour, sugars, and baking powder. In a small bowl, beat together the egg, milk, margarine, and sour cream. Stir into the dry ingredients and mix only until the dry ingredients are moistened. Fold in the chocolate chips and nuts, if using. Spoon into the muffin cups.
Bake for 15 to 20 minutes. Serve warm.
Alternately, you can dress them up with some frosting.