Preheat and prep: Heat your oven to 350°F (175°C). Lightly grease a mini muffin pan or donut hole pan with nonstick spray.

Mix the dry ingredients: In a medium bowl, whisk 1¼ cups all-purpose flour, ¼ cup granulated sugar, 2 tablespoons brown sugar, 1½ teaspoons baking powder, ¼ teaspoon baking soda, ½ teaspoon kosher salt, ½ teaspoon ground cinnamon, and a pinch of nutmeg if using.

Mix the wet ingredients: In a separate bowl, whisk ½ cup buttermilk, 1 large egg, 1 teaspoon vanilla extract, and 3 tablespoons melted unsalted butter (slightly cooled).

Combine: Pour the wet ingredients into the dry. Stir gently with a spatula until just combined. Do not overmix; a few small lumps are fine.

Portion: Spoon the batter into the pan, filling each well about ¾ full. A small cookie scoop works great for even portions.

Bake: Bake for 9–12 minutes, until the tops spring back lightly and a toothpick comes out clean. Avoid overbaking to keep them soft.

Make the coating: While they bake, melt 3 tablespoons unsalted butter in a small bowl. In another bowl, combine ½ cup granulated sugar with 1–1½ teaspoons ground cinnamon (adjust to taste).

Coat: Let the donut holes cool for 3–4 minutes in the pan, then transfer to a rack. Brush or dip each one lightly in melted butter, then roll in the cinnamon sugar until well coated.

Serve: Enjoy warm for the best texture and flavor. Repeat coating if you like a thicker sugar crust.