In a small bowl, cream butter and sugar. Add egg and lemon zest; beat well. Combine the flour, baking powder and salt; add to creamed mixture alternately with milk.
Transfer to a 5-3/4x3x2-in. loaf pan coated with cooking spray. Bake at 350° for 40-45 minutes or until a toothpick inserted in the center comes out clean. Cool for 10 minutes before removing from pan to a wire rack. Combine glaze ingredients; drizzle over warm bread.