1/3 cup sugar
1/4 cup flour
2 tablespoons butter or margarine
In a large bowl, combine flour, sugar, baking powder, baking soda and salt. Combine eggs yogurt and oil; mix well. Stir into dry ingredients just until moistened. Fold in blueberries. Fill greased muffin cups three-fourths full.
For topping, combine sugar and flour. Cut in butter until mixture resembles course crumbs; sprinkle about 1 tablespoon over each muffin.
Bake at 400° for 18-20 minutes or until done. Cool in pan 10 minutes before removing to wire rack. Yield: 1 dozen.