For the donuts, preheat the oven to 325F and grease a 12-cavity donut pan. (If you only have a 6 cavity pan, you will need to work in batches)
In a blender, combine the sour cream, eggs, sweetener, and vanilla extract. Pulse to combine.
Add the almond flour, baking powder, spices, and salt and blend until well combined. If your batter is very thick, add water until it thins out. It should be scoopable but not pourable.
Spoon the batter into the donut cavity to about 3/4 full. Bake about 20 minutes, until golden brown and just firm to the touch. Remove and let cool in the pan 10 minutes, then flip out onto a wire rack to cool completely.
For the coating, in a small bowl combine the sweetener and cinnamon. Brush the top of each donut with melted butter and then sprinkle with the sweetener mixture.
Serving Size Makes about 12 donuts, depending on the size of your donut pan.
Servings 1
* Percent Daily Values are based on a 2,000 calorie diet. Your daily value may be higher or lower depending on your calorie needs.