Add remaining 1 tablespoon butter to pan and cook until lightly browned. Re-whisk eggs until foamy, then add to skillet and cook, using a silicone spatula to push the edges in toward the center as they set and tilting the pan to spread the uncooked egg underneath. Continue pushing in the edges of the eggs and tilting the skillet, working all around the pan, until omelette is almost set, about 45 seconds.

Sprinkle ham and cheese over half of omelette, remove from heat, cover, and let omelette sit until it reaches the desired consistency, about 1 minute.

Using silicone spatula, loosen the edges of the omelette from skillet and shake skillet to ensure that it’s not stuck. Carefully fold omelette in half, then slide it onto a serving plate and serve immediately.

Special equipment
10-inch nonstick skillet, silicone spatula

Finishing the omelette off-heat keeps it tender and moist.
Just as with scrambled eggs, the method by which the eggs are heated and stirred is the primary factor that determines what kind of omelette you end up with. This is my basic technique for diner-style omelettes with large, tender, browned curds and plenty of space for fillings.
This recipe is excerpted from my book, The Food Lab: Better Home Cooking Through Science.