For the coating: 1/2 cup granulated sugar, 1 tablespoon cinnamon, and 4 tablespoons melted butter
Instructions
Reduce the Apple Cider: Pour the apple cider into a small saucepan over medium-high heat. Simmer until the liquid has reduced to exactly 1/2 cup. This should take about 10-12 minutes. Set it aside to cool slightly.
Prepare the Oven and Pan: Preheat your oven to 350°F (175°C). Lightly grease a 24-count mini-muffin tin with non-stick cooking spray or a little bit of butter to ensure the donut holes pop out easily.
Whisk Dry Ingredients: In a large mixing bowl, whisk together the flour, sugar, baking powder, cinnamon, salt, and nutmeg. Make sure there are no large clumps of flour or spices left in the mixture.
Mix Wet Ingredients: In a separate medium bowl, whisk together the cooled reduced apple cider, egg, melted butter, milk, and vanilla extract until well combined.
Combine into Batter: Pour the wet ingredients into the dry ingredients. Use a spatula to gently fold the mixture together until just combined. Be careful not to overmix, as this can make the donut holes tough.
Scoop and Bake: Fill each mini-muffin cup about 3/4 full with the batter. Bake for 12 to 15 minutes, or until a toothpick inserted into the center comes out clean. Let them cool in the pan for 5 minutes.
Coat in Cinnamon Sugar: While the donut holes are still warm, melt the additional butter in a small bowl. In another bowl, mix the sugar and cinnamon. Brush each donut hole with butter, then roll it in the cinnamon-sugar mixture until fully coated.