Beat the eggs very well with a whisk or fork in a small bowl and set aside.
Place the butter in a shallow bowl or a glass pie plate and microwave for 10 to 15 seconds just to melt the butter. Remove the bowl or plate from the microwave, swirl the butter around to coat the bottom of the dish, pour in the beaten eggs, and cook in the microwave for 30 to 45 seconds or until the outer edge of the eggs are just cooked.
Remove the dish from the microwave, gently stir the cooked egg into the runny egg and sprinkle on the ham and gruyere. Place the dish back into the microwave and cook on high for another 2 minutes or until the eggs are firm and fully cooked.
Remove the omelette from the oven, sprinkle with the chives, season with salt and pepper, and loosen the edges of the omelette with a spatula. Slide the omelette out of the dish onto a plate and dig in!