WHISK eggs with water until well blended.
MELT margarine in small skillet on medium heat. Add eggs; cook 2 to 3 min. or until almost set, lifting edge with spatula and tilting skillet to allow uncooked portion to flow underneath.
TOP with cheese. Slip spatula underneath omelette, tip skillet to loosen and gently fold omelette in half. Slide or flip omelette onto serving plate.