Preheat the oven to 350ºF and grease 10 wells of a non-stick donut pan. If yours only holds 6 like mine, you may need to work in batches.
In a large bowl, whisk together the pumpkin, butter, sweetener, eggs, and vanilla extract until well combined.
Add the almond flour, protein powder, baking powder, and salt and stir until well mixed. Add water 1 tablespoon at a time until you have a thick but easily scoopable consistency. It should be like a thick cake batter.
Spoon the batter into the prepared pan, filling the donut wells about ¾ full. Bake 15 to 20 minutes, or until the tops are just firm to the touch.
Remove and let cool in the pan 15 minutes before transferring to a wire rack to cool completely.
In a shallow bowl, whisk together the sweetener, pumpkin pie spice, and cinnamon. Brush the donuts with the melted butter on both sides, then dip into the sweetener mixture.
You can also simply sprinkle the sweetener mixture overtop the donuts.
