Preheat oven to 375. Generously grease cups of a stone 12-cup muffin pan or use a regular 12-cup pan with liners.
In a medium mixing bowl, beat eggs on low speed until frothy (30 seconds), and add milk, oil, lemon zest and vanilla. Beat until blended.
In another bowl mix all the dry ingredients except the blueberries. With the mixer on low, slowly add the dry ingredient mixture into wet ingredients until smooth. It will be thick and sticky. Gently stir in the blueberries. Divide batter evenly into the 12 muffin cups. Add topping to each cup.
Bake 25-30 minutes or until muffin tops are firm. Cool muffins for 10 minutes before removing from pan.