Prep your pan. Heat the oven to 350°F (175°C). Grease a mini muffin tin or line it with mini liners. If air-frying, line the basket with parchment and preheat to 330°F (165°C).

Mix the dry ingredients. In a bowl, whisk 1 3/4 cups oat flour, 1 1/2 teaspoons baking powder, 1/4 teaspoon baking soda, 1/4 teaspoon salt, and 1 teaspoon cinnamon. Break up any clumps for a smooth batter.

Combine the wet ingredients. In another bowl, whisk 1/2 cup sugar (or 1/4 cup sugar + 1/4 cup light brown sugar), 2 eggs, 1/2 cup milk, 1/3 cup plain yogurt, 1 teaspoon vanilla, and 3 tablespoons melted butter or oil until smooth.

Bring it together. Pour the wet mixture into the dry. Stir gently until just combined. The batter should be thick but scoopable; add a tablespoon of milk if it looks dry.

Fill and bake. Spoon the batter into the mini muffin cups about 3/4 full. Bake 10–12 minutes until the tops spring back and a toothpick comes out clean. For the air fryer, drop 1-tablespoon scoops onto parchment and cook 7–9 minutes, flipping once.

Make the coating. Mix 1/2 cup granulated sugar with 1–2 teaspoons cinnamon in a shallow bowl. Melt 3 tablespoons butter in a separate bowl.

Coat while warm. Let donut holes cool for 3–4 minutes. Brush or toss lightly with melted butter, then roll in the cinnamon sugar until well coated.

Serve. Enjoy warm for the best texture. They’re soft, fragrant, and perfect as-is.