Streusel-Topped Blueberry Muffins

Directions

1. In a large bowl, butter and sugar until crumbly, about 2 minutes. Add egg and sour cream; mix well. Combine the flour, baking powder and baking soda; add to sugar mixture just until combined. Fold in blueberries.
2. Fill paper-lined muffin cups two-thirds full. For topping, combine brown sugar and flour in a small bowl; cut in butter until crumbly. Sprinkle over batter.
3. Bake at 350° for 20 minutes or until a toothpick inserted in the center comes out clean. Cool for 5 minutes before removing from pan to a wire rack. Combine glaze ingredients; drizzle over warm muffins.