Gently beat 2 of the eggs with 1 tbsp (15 mL) water and a pinch each salt and pepper. In 8-inch (20 cm) nonstick skillet, melt 1 tsp (5 mL) butter over medium-high heat. Pour eggs into skillet; cook, stirring constantly with small heatproof spatula or fork, until eggs are almost set but still moist. Sprinkle with half of the cheese and top with half each of the ham and asparagus. Using spatula, gently loosen one edge of omelette from side of pan; starting at loosened edge, fold one-third of omelette over filling. Fold the second third over while rolling omelette onto warmed plate; tent with foil and let stand until cheese melts, about 1 minute. Repeat with remaining ingredients.