In a large bowl, cream butter and sugar until light and fluffy. Beat in eggs. Combine the flour, baking powder, baking soda and lemon zest; add to creamed mixture alternately with yogurt and milk. Gently fold in raspberries.
Fill greased or paper-lined muffin cups three-fourths full. Combine the topping ingredients; spoon over batter. Bake at 375° for 25-30 minutes or until a toothpick inserted in the center comes out clean. Cool for 5 minutes before removing from pans to wire racks. Serve warm.