Preheat oven to 375 degrees. Prepare muffins tins with either paper liners or nonstick baking spray.
Combine flour, baking powder, salt and lemon zest in a bowl, mixing well.
In a mixer, cream together butter and sugar until light and creamy. Add eggs, milk, vanilla and lemon juice. Mix until well incorporated.
Add dry ingredients to the mixer and mix just until combined.
Fold in the blueberries by hand. Scoop by ¼ cup into muffin tins.
Combine topping ingredients, crumbling together by hand or with the tines of a fork. Sprinkle onto the muffins.
Bake 20 minutes or until lightly browned on top. Cool on rack for 5 minutes and remove from muffin tin to cook directly on the rack.