Step 1

Preheat the oven 400 degrees Fahrenheit.

Step 2

Line 12 muffin cups with muffin papers or spray with cooking spray.

Step 3

In a medium mixing bowl, whisk together the eggs and sugar until fluffy.

Step 4

Add the sour cream, oil, and vanilla and whisk to combine.

Step 5

In a larger mixing bowl, stir together the flour, baking powder, baking soda, and salt.

Step 6

Add the wet ingredients and stir just until combined.

Step 7

Gently fold in the blueberries.

Step 8

Divide batter among the muffin cups.

Step 9

Cut butter into the flour, brown sugar, salt, and cinnamon until the mixture resembles course crumbs.

Step 10

Place1-2 tablespoons on the top of the muffin batter in each muffin cup.

Step 11

Bake for 18-22 minutes until a toothpick inserted in the center comes out clean.