Preheat your oven to 375°F (190°C). Line a muffin tin with paper liners or grease it lightly with butter or cooking spray.

In a large mixing bowl, combine the flour, sugar, baking powder, and salt. In another bowl, whisk together the vegetable oil, egg, milk, and vanilla extract. 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, sugar, and cinnamon for the crumble topping. Add the cold butter and use your fingers or a fork to work it into the dry ingredients until the mixture resembles coarse crumbs.

Divide the muffin batter evenly among the prepared muffin cups, filling each about ⅔ full. Sprinkle the crumble topping generously over each muffin.

Bake in the preheated oven for 18-20 minutes, or until a toothpick inserted into the center of a muffin comes out clean. Allow the muffins to cool in the pan for 5 minutes before transferring them to a wire rack to cool completely.