Preheat the oven to 350 degrees.

Add the almond flour, protein powder, powdered sugar substitute, baking powder, melted butter, eggs, 1/4 cup heavy whipping cream, 1 teaspoon vanilla extract and 1/2 teaspoon cinnamon in a mixing bowl, and beat on high until a smooth batter is formed.

Fill the sections of a donut baking pan to the top, and bake for 15-20 minutes until browned and completely cooked through.

Let the donuts cool completely.

Add the 4 tablespoons of heavy whipping cream and 6 tablespoons of powdered sugar substitute to a mixing bowl, and beat on high until smooth and creamy.

Dip the top of the donuts into the glaze mixture, and set the donuts on a rack to allow the glaze to set.

Mix together the granulated sweetener and 1/2 teaspoon of cinnamon in a small bowl, and sprinkle it on top of the donuts before the glaze has completely set.