Preheat oven to 400 degrees F. Grease a muffin tin with butter and set aside. In a medium bowl stir together dry ingredients and set aside. In a small bowl, combine wet ingredients, then add to the dry ingredients, stirring gently until the mixture is just moistened. Fill muffin cups 2/3 full. Bake for 15 minutes, or until lightly browned and a wooden toothpick inserted in centers comes out clean.