1. Preheat the oven to 230°C.
2. The egg white and yolk are separated.
3. Grind the cheese into filaments.
4. Whip the egg whites until dry foaming.
5. Stir the cheese gently into the egg whites.
6. Put the egg whites on the baking tray with a spoon, dig a small hole in the middle, and leave it for the egg yolk. Bake in the oven for 3 minutes.
7. Add the egg yolk and bake for another 3 minutes.
1. The egg can be sweet or salty. For sweetness, add sugar during the process of whisking the egg;
2. Gruyere cheese can be replaced with any kind of hard cheese;
3. The eggs should be eaten while they are hot, otherwise, like me, they can only be eaten until they are soft.