Preheat the oven to 375°F. Lightly spray a 12-count donut pan with cooking spray.

In a large mixing bowl, add the self-rising flour, cottage cheese, milk, and sugar (if using). Mix until a thick dough remains. If the dough is too thick, add a tablespoon or two more of milk. If it is too thin, add an extra tablespoon of flour.

Transfer the donut batter to the donut pan. Bake for 15-17 minutes or until they bounce back and are golden around the edges. Remove from the oven.

While the donuts are baking, whisk the sugar and cinnamon to a bowl.

Spray all sides of the donuts with cooking spray or melted butter. Moving quickly, dip each donut in the cinnamon sugar mixture, ensuring all both sides are coated.