Place a rack in the center of the oven and preheat to 375 degrees. Coat a standard-size muffin tin with cooking spray and set aside.

Whisk together flour, sugar, baking powder, baking soda and salt in a medium bowl then set aside.

In a smaller mixing bowl, whisk eggs, milk, vanilla and melted butter until combined. Add the wet ingredients to the bowl containing the dry ingredients and fold until just combined. Mix in blueberries then divide batter evenly into the muffin tin.

In a small bowl, mix sugar, flour and butter with a fork until completely combined and crumbled. Sprinkle topping over the muffins.

Bake 18–20 minutes or until the centers are firm and spring back when pressed. Cool muffins for 5 minutes then remove from the pan and transfer to a wire rack to cool completely.