In a large bowl, combine the flour, sugars, baking powder, cinnamon and salt. In a small bowl, whisk the egg, milk and butter. Stir into dry ingredients just until moistened. Fold in blueberries and lemon zest. Fill greased or paper-lined muffin cups two-thirds full.
Combine topping ingredients; sprinkle over batter. Bake at 350° for 20-25 minutes or until a toothpick comes out clean. Cool for 5 minutes before removing from pan to a wire rack. Combine glaze ingredients until smooth; drizzle over warm muffins.