Step 1

Preheat oven to 350°F. Lightly grease a doughnut pan with nonstick cooking spray and set aside.

Step 2

Melt 3 tablespoons butter in a small saucepan over medium-low heat, stirring occasionally. Butter will crackle and foam a bit as it browns. Once butter is light brown and smells nutty, remove from heat and immediately transfer to a small bowl. Be careful, it goes from brown butter to black burnt butter quickly.

Step 3

In a medium mixing bowl, whisk together flour, sugar, baking powder, baking soda, salt, and cinnamon.

Step 4

In a small mixing bowl, whisk together egg, buttermilk, and vanilla extract. Measure out 2 tablespoons of the browned butter and whisk into the wet ingredients.

Step 5

Add wet ingredients to dry ingredeints. Stir together until ingredients are well combined, but do not overmix.

Step 6

Spoon batter into a large ziploc bag and use a scissor to cut about a 1/2″ piece off one corner to create a makeshift disposable pastry bag. Fill each well in the doughnut pan approximately 3/4 full. Alternatively, use a spoon to fill donut pan and smooth out batter.

Step 7

Place in the oven and bake for 9-12 minutes, until a toothpick inserted into doughnut comes out clean. Remove from the oven and allow to cool in the pan before inverting onto a wire rack to cool completely.

Step 8

Combine sugar, brown, sugar, and cinnamon in a small bowl. Melt remaining 3 tablespoons butter in another small bowl. Working one at a time, lightly brush doughnut with butter, and roll around in sugar mixture until evenly coated.

Step 9

Devour immediately or store at room temperature in a ziploc bag. But really, devour immediately.