Preheat the oven to 375°F (190°C). Lightly grease a mini muffin pan with cooking spray and set aside.
Mix the dry ingredients. In a medium bowl, whisk together the flour, monkfruit brown sugar, baking powder, pumpkin pie spice, and salt.
Combine the wet ingredients. In a separate large bowl, whisk the egg. Add pumpkin puree, milk, and vanilla, and mix until smooth.
Bring it together. Stir the dry mixture into the wet ingredients until just combined. Fold in the melted butter until evenly incorporated.
Fill the pan. Spoon about 1 tablespoon of batter into each mini muffin tin. Can use a small cookie scoop to make them more round.
Bake for 10–12 minutes, or until a toothpick inserted into the center comes out clean or with a few moist crumbs.
Cool slightly. Let the donut holes rest for a few minutes in the pan before transferring to a wire rack.
Make the coating. In a shallow dish, combine the sugar and cinnamon. Melt the butter in a separate bowl.
Coat the donuts. Dip each donut hole in the melted butter (shake off excess), then roll in the cinnamon sugar until fully coated.
Serve & enjoy. Best eaten warm, but still delicious at room temperature.