Heat the oil in a large skillet over medium heat. If the sausage is in link form, remove it from the casings. Add the sausage and cook, stirring and chopping it into small pieces, until browned, about 10 minutes. Drain any excess fat and set the meat aside to cool.
Preheat the oven to 400ºF. Line a standard 12-cup muffin pan with parchment paper liners.
Whisk together the eggs, cottage cheese, and water in a large mixing bowl. Then stir in the cheddar, onions, and cooked sausage.
In a small bowl combine the flour, baking powder, and salt, and then stir and fold it into the sausage mixture until it forms a thick batter. Do not overmix!
Divide the batter evenly between the muffin cups, using about 1/4 cup for each.
Bake 20 to 23 minutes, until the muffins are set and just starring to brown on top.
Cool completely, then pack into a freezer bag and freeze.
To serve: these muffins are best served warm. Thaw overnight in the fridge and then heat for 20 seconds in a microwave, or thaw on the defrost setting in a microwave.