In a medium bowl, beat eggs. Add cottage cheese and set aside. Heat a large skillet over medium heat. Add half the margarine. Add onions and cook until transparent. Add spinach to the pan and cook until just wilted, about one minute. Place onion and spinach mixture in a small bowl and set aside. Add remaining butter to skillet, lower heat to medium-low, and add the egg and cottage cheese mixture. Using a heat-proof spatula, gently scramble egg mixture until cooked. Add spinach and onion mixture back to pan and mix with eggs. Place this mixture in the center of the tortilla, fold in the sides, then roll up.