Preheat oven to 350 degrees F. Lightly oil a mini muffin pan or coat with nonstick spray.
In a large bowl, combine flour, cinnamon, nutmeg, allspice, cloves, baking powder and salt.
In a large glass measuring cup or another bowl, whisk together pumpkin puree, milk, brown sugar, canola oil, egg and vanilla.
Pour mixture over dry ingredients and stir using a rubber spatula just until moist.
Scoop the batter evenly into the muffin tray.
Place into oven and bake for 10-12 minutes, or until a tester inserted in the center comes out clean.
When the muffins are done, cool for 2 minutes and dip each muffin into the melted butter and then into the cinnamon sugar topping.
Let cool on a wire rack.
For the cinnamon sugar topping
In a medium bowl, combine cinnamon and sugar.
Notes
Use a small cookie scoop. Using a small cookie scoop is a convenient way to transfer the batter to the mini muffin tin with ease and less mess.
Avoid pumpkin pie filling. Canned pumpkin puree and pumpkin pie filling are not the same, and are not interchangeable. Be sure to use 100% pure pumpkin as pumpkin pie filling comes pre-mixed with sweeteners and spices.
Combine just until moist. Using a rubber spatula, stir the batter until everything is just combined and moistened with a few lumps here and there. Over-mixing will lead to dense, tough donut holes.
Fill 3/4 full. Fill each cavity in the mini muffin pan about 3/4 full to give the batter room to rise without spilling over the edges.
Dip and roll just before serving. To avoid soggy donuts, coat the donut holes in butter and cinnamon sugar just before serving. Plain, uncoated donuts will store much better.