Directions:

Preheat your oven to 425.

Line a large muffin tin with parchment paper and greas it with olive oil.

In a bowl, whisk butter and sugar until well combined.

Add the eggs and whisk for 2 to 3 minutes or until it is a pale color.

Add the milk, vanilla, sour cream, and oil, then mix until well combined.

In another bowl, combine flour, baking powder, baking soda, and salt.

Save 2 tablespoons of this dry mixture to coat the blueberries.

Pour the wet mixture into the dry ingredients and mix until just combined.

Toss the blueberries in the reserved 2 tablespoons of dry mixture.

Add the blueberries to the batter. Do not overmix the batter.

Let the batter sit at room temperature for 30 minutes.

Do not mix the batter again.

For the Crumb Topping:

In a bowl, mix melted butter, sugar, and brown sugar.

Mix well, then add flour and cornstarch.

Mix again until crumbly and coarse.

Pour the batter evenly among the muffin cups.

Bake for 5 minutes, then reduce the oven temperature to 375 without opening the oven door.

Continue baking for an additional 15 minutes or until a toothpick inserted in the center comes out clean.

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