Steps
- Preheat the broiler to high. Separate 3 large eggs; whisk the yolks with salt and black pepper, then beat the whites in a clean bowl until soft peaks form.
- Warm a broiler-safe skillet with a 7in / 18cm base over low heat. Add 10g of unsalted butter and raise the heat to medium.
- Gently fold the yolks, 25g of finely grated mature cheddar, half of 25g of finely grated Parmesan, and 1½ tablespoons of finely snipped chives into the whites.
- When the butter foams, spoon in the egg mixture and shake the pan to level it. Cook for about 1 minute, until the base sets.
- Loosen the edges and scatter over 25g of finely grated Gruyère. Broil 4in / 10cm from the heat for about 1 minute, until the cheese melts and turns golden.
- Loosen the omelette and fold in half onto a plate. Sprinkle with the remaining Parmesan.