Preheat oven to 375 degrees F (190 degrees C). Grease 12 muffin cups or line with paper muffin liners.
Combine 2 cups flour, 2 teaspoons baking powder, and 1/2 teaspoon salt in medium bowl. In a small bowl, sprinkle 1 to 2 tablespoons flour over blueberries, and set aside. (This simple trick will keep you from having “purple” batter)
In a large bowl, beat 1/2 cup butter with 3/4 cup sugar until light and fluffy. Beat in eggs, and stir in vanilla and lemon zest. Fold in dry ingredients alternately with milk. Fold in blueberries.
Remember, fold gently, don’t stir. Spoon batter into prepared cups.
Combine 2 tablespoons flour, 5 tablespoons sugar ,and 1/2 teaspoon cinnamon in a small bowl. Cut in 2 tablespoons butter with fork or pastry blender until mixture resembles course crumbs. Sprinkle over batter in muffin cups.
Bake in the preheated oven for 20 to 25 minutes, or until a toothpick inserted in centre of a muffin comes out clean. Cool in pans on wire rack. These muffins freeze really well, and re-heat in the microwave successfully.