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

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

In another bowl, mix the milk, oil, eggs, and vanilla extract until well combined.

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

In a small bowl, mix together the flour, brown sugar, melted butter, and cinnamon until crumbly.

Spoon the muffin batter into the prepared muffin tin, filling each cup about 2/3 full.

Sprinkle the streusel topping evenly over each muffin.

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

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