Step 1

Preheat the oven to 400°F. Line a muffin pan with 12 paper liners.

Step 2

In a large bowl, whisk together the flour, baking powder, and salt. Set aside.

Step 3

In a medium bowl, whisk together the melted butter, oil, sugar, milk, sour cream, eggs, and vanilla.

Step 4

Fold the dry ingredients into the wet ingredients.

Step 5

Gently fold in the blueberries. Fill the muffin liners 3/4 of the way full. Set aside.

Step 6

In a bowl, mix together all the ingredients for the crumb topping with a fork until combined.

Step 7

Sprinkle about one tablespoon of the crumb topping over each muffin.

Step 8

Bake the muffins for about 20 minutes, or until they are baked through. Allow the muffins to cool for 5-10 minutes in the pan before transferring to a wire rack to continue cooling. Enjoy!