Cream butter; gradually add sugar, beating until light and fluffy.
Add the eggs, one at a time, beating well after each addition.
Combine flour and baking powder; set aside.
Combine buttermilk and soda; add to creamed mixture alternately with flour mixture, beginning and ending with flour mixture.
Stir in remaining ingredients.
Fill greased muffin pans two-thirds full.
Bake at 400Â° for 15 to 20 minutes.