Preheat your oven to 350ºF (175ºC) and spray a donut pan with non-stick cooking spray.

In a medium bowl, combine pumpkin puree, brown sugar, vegetable oil, and milk. Whisk until smooth and creamy.

In a large bowl, whisk together the flour, baking powder, pumpkin pie spice, cinnamon, nutmeg, and salt.

Gradually add the dry ingredients to the wet mixture and mix until just combined.

Fill each cavity of the prepared donut pan evenly with the batter, about two-thirds full.

Bake for 15-16 minutes or until the donuts spring back when lightly touched and a toothpick comes out clean.

Let cool in the pan for about 10 minutes, then transfer to a wire rack to cool for another 10 minutes.

Mix the granulated sugar and cinnamon in a bowl. Brush the warm donuts with melted butter and roll in the cinnamon sugar.