Cook spinach, onions and garlic in a small nonstick skillet on medium heat. Stir frequently and once onions look tender, add tomatoes.
Whisk eggs and cottage cheese together. Add to skillet; tilt to evenly coat spinach mixture.
Cook 2-3 minutes, covered, or until eggs are almost set. Top with 3 tbsp cheese; cook 1 minute more. Slip spatula underneath omelette to loosen and gently fold omelette in half. Remove from heat; cut in half.