Crack the eggs into a bowl and whisk very well, until streaks no longer appear. Mix in the cheese, oil, salt, and a grind of pepper.

If you have sauced spaghetti, heat it in a skillet with water until warm, then mix in with the egg mixture. For plain spaghetti, crisp it in the skillet before adding the egg mixture.

Turn the heat to low and rotate the skillet occasionally. Cook until the perimeter looks set and the center is still somewhat liquid, about 8 minutes.

Flip the frittata onto a plate and then slide it back into the skillet. Keep cooking on low heat for about 7 more minutes.

Check if the egg is set by making a crack in the middle with a spatula. Slice and serve once cooled.