Step 1

Preheat the oven to 350°F and spray a mini donut pan with cooking spray before setting it aside.

Step 2

Stir together the flour, sugar, baking powder, and salt in a large mixing bowl.

Step 3

Add the egg, sour cream, milk, 1 tablespoon melted butter, vanilla, and ground cinnamon to the dry ingredients and whisk until well combined with no dry patches.

Step 4

Transfer the batter into a piping bag and snip off the tip. Pipe the mini donut batter into the prepared pan, making sure each donut mold gets about ⅔ full. You should get 15 donuts out of this batter

Step 5

Place the pan in the oven and bake for 8-9 minutes, or until they're lightly browned and a toothpick can be inserted into the center and comes out clean.

Step 6

While the mini donuts are baking, in a medium-sized mixing bowl, stir together the sugar and cinnamon for the donut coating.

Step 7

When the donuts are finished baking, remove them from the oven and take the donuts out of the pan while they're still hot. Working one by one, lightly brush some of the remaining melted butter on the outside of the mini baked donut. Then quickly and immediately place the butter brushed donut into the cinnamon sugar mixture and toss it around to coat.

Step 8

Repeat this process with the remaining donuts, and serve immediately.