Preheat the oven to 375°F (190°C) and line a muffin tin with paper liners.

In a large mixing bowl, whisk together the flour, sugar, baking powder, and salt.

In another bowl, combine the milk, melted butter, eggs, and vanilla extract.

Pour the wet ingredients into the dry ingredients and mix until just combined. Gently fold in the blueberries.

In a small bowl, mix together the flour, brown sugar, and cinnamon.

Add the cold butter and use a fork or your fingers to blend until the mixture resembles coarse crumbs.

Divide the muffin batter evenly among the muffin cups.

Sprinkle the crumble topping over each muffin.

Bake for 18-20 minutes, or until a toothpick inserted into the center comes out clean.

Allow to cool in the pan for 5 minutes before transferring to a wire rack to cool completely.