Start by preheating your oven to 350°F (175°C). Lightly grease 10 wells of your donut pan. If your pan is smaller, you can bake these in batches.
In a spacious bowl, whisk together the pumpkin puree, 6 tablespoons of melted butter, your brown sugar replacement, eggs, and vanilla extract until the mixture is smooth and well blended.
Add the almond flour, protein powder, baking powder, 2 teaspoons of pumpkin pie spice, and salt to the wet mixture. Stir gently until everything is just combined.
Gradually add the water, one tablespoon at a time, mixing after each addition. You're looking for a thick consistency, much like a rich cake batter – easy to scoop, but not too runny. The amount of water needed can vary!
Carefully spoon the batter into your prepared donut wells, filling each about three-quarters full. Bake for 15 to 20 minutes, or until the donut tops feel firm to the touch.
Let your freshly baked donuts cool in the pan for about 15 minutes. This helps them set. Then, gently transfer them to a wire rack to cool completely.
While the donuts are cooling, combine the granulated sweetener, 1/2 teaspoon pumpkin pie spice, and cinnamon in a shallow bowl. Whisk them together until evenly mixed.
Once the donuts are cool, brush both sides of each donut with the remaining 2 tablespoons of melted butter. Immediately dip them into your spiced sweetener mixture, making sure they're fully coated. If you prefer, you can simply sprinkle the mixture over the donuts instead.
Your easy, healthy pumpkin spice donuts are ready to be savored!