Preparation Preheat oven to 400°F. and butter twelve 1/3-cup muffin cups. Into a bowl sift together flour, sugar, baking powder, baking soda, and salt. Melt butter and in a small bowl whisk together with sour cream, egg, and vanilla. Stir butter mixture (and additional ingredients; see note, above) into flour mixture until just combined. Divide batter among muffin cups and bake in middle of oven until golden and a tester comes out clean, about 20 minutes.
Preparation Preheat oven to 400°F. and butter twelve 1/3-cup muffin cups. Into a bowl sift together flour, sugar, baking powder, baking soda, and salt. Melt butter and in a small bowl whisk together with sour cream, egg, and vanilla. Stir butter mixture (and additional ingredients; see note, above) into flour mixture until just combined. Divide batter among muffin cups and bake in middle of oven until golden and a tester comes out clean, about 20 minutes.