Blueberry Muffins with Cinnamon Crumb Topping

Gather all ingredients.

Preheat the oven to 400°F (200°C). Grease 8 muffin cups or line with paper liners.

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

In a small liquid measuring cup, combine oil, egg, and enough milk to reach the 1-cup mark. Stir until combined.

Pour the liquid mixture into the flour mixture and mix just until the batter is combined. Fold in blueberries; set aside the batter.

For the crumb topping, in a small bowl, mix together sugar, flour, butter, and cinnamon. Use a fork to create a crumbly texture.

Spoon the batter into prepared muffin cups, filling each cup to the top. Sprinkle with crumb topping.

Bake until a toothpick inserted in the center of a muffin comes out clean, 20 to 25 minutes.