Step 1

Preheat oven to 425 degrees F.

Step 2

Generously grease a jumbo 6-count muffin pan with butter or nonstick spray, or line with muffin liners. Set aside.

Step 3

Whisk the flour, baking powder, baking soda, salt, and cinnamon together in a large bowl. Set aside.

Step 4

Whisk the melted butter, oil, sugar, and eggs together until combined.

Step 5

Then whisk in the sour cream, milk, and vanilla extract. the mixture will be pale yellow.

Step 6

Pour the wet ingredients into the dry ingredients and fold together with a rubber spatula or wooden spoon until completely combined.

Step 7

Use a whisk to get rid of any large lumps of flour, if needed. Avoid overmixing.

Step 8

The batter will be thick. Fold in the blueberries.

Step 9

Divide the batter between each muffin cup, filling all the way to the top.

Step 10

Sprinkle with coarse sugar, if desired.

Step 11

Bake at 425 degrees F for 5 minutes, then, keeping the muffins in the oven, reduce the oven temperature to 350 degrees F and continue to bake for 25 to 30 minutes, or until the tops are lightly golden brown and centers are set.

Step 12

Stick a toothpick in the center of a muffin to test for doneness.

Step 13

If it comes out clean, the muffins are done.

Step 14

Allow to cool for 10 minutes in pan before serving.