Cook the spaghetti in a tall saucepan with plenty of water and a good handful of salt. We leave them al dente after cooking for about eight minutes, since they will finish cooking in the oven when the frittata curdles. While they cook, preheat the oven to 150ºC.
We cook the pancetta or bacon – even better if you get the authentic Italian guiancale – and brown them in a pan without oil, taking advantage of their own fat. On the other hand, in a bowl, beat the eggs with the cheese, the pepper and a pinch of salt and add the bacon and its fat when they have cooled down, to prevent the heat from starting to curdle the egg.
In a skillet suitable for the oven, put the butter and lightly sauté the cooked and well-drained pasta. Then we distribute it evenly and cover it with the contents of the bowl of beaten eggs with the rest of the ingredients.
We bake at a temperature of 150º so that the spaghetti omelette curdles very slowly so that it is very juicy and tender. It will be necessary to leave it for about 30 or 35 minutes so that it is ready. If you want, you can turn it over halfway through cooking like a traditional potato omelette. This fritatta, served hot but lukewarm or cold, is also delicious. If you have any leftover, you can reheat it or use it to make an original recipe for it, adding mayopesto sauce and mixing well.