1.Boil, steam or microwave asparagus until tender; drain.
2.Meanwhile, in a medium bowl, lightly whisk eggs, cream, the water, cheeses and half the chives until combined. Season.
3.Heat a quarter of the butter and 1 tsp of the oil in a small frying pan over medium-high heat. When the butter is just bubbling, add a quarter of the egg mixture; tilt pan to cover base with egg mixture. Cook over medium heat until omelette is just set. Place a quarter of both the asparagus and ham on one side of the omelette. Use a spatula to lift and fold the omelette in half over asparagus and ham; cook a further 30 seconds. Carefully slide omelette onto a serving plate. Wipe out the pan.
4.Repeat with remaining butter, oil, egg mixture, asparagus and ham (wiping out the pan after each omelette), to make a total of four omelettes. Serve immediately topped with remaining chives.
Using a mixture of butter and oil stops the butter from burning. Don’t overbeat the eggs or the omelette will be tough.Note