Preheat oven to 425.
Grease an entire 12 count muffin tin, including the rim, with non stick spray or shortening.
Prepare topping by mixing together the sugar, flour, and cinnamon in a small bowl. Stir in melted butter. It should resemble a crumbly mixture. Set aside.
In a large bowl, whisk flour, baking powder, baking soda, and salt.
In a medium bowl, stir the melted butter with the sugar. Add eggs, milk, and vanilla. Mix thoroughly.
Add wet ingredients to dry ingredients and stir gently until mostly combined. Fold in the blueberries.
Pour batter equally into 12 muffin cups. Fill all the way to the top.
Sprinkle about 1 teaspoon of the topping over the batter.
Bake for 5 minutes at 425, then, while the muffins are still in the oven, lower heat to 375 and bake additional 15 minutes or until an inserted toothpick comes out clean.
Allow to cool about 10 minutes, then transfer to wire rack. Enjoy!