Finishing a pasta dish by tossing all the ingredients together in the hot skillet or saucepan is a tried-and-true technique for intensifying flavor. In most cases, that is. For certain preparations, like spaghetti alla carbonara, that call for raw fresh eggs or egg yolks, you want to finish mixing the ingredients in a bowl instead of a skillet. Bringing those eggs into contact with the hot cooking surface risks curdling them, marring the sauce's silky texture. The technique is simple. 1. Base ingredients like oil and pork (in the case of carbonara, that would be guanciale or pancetta) should be cooked in a skillet first, to render the fat, but once you've done that, the contents of the skillet should be transferred to a big bowl and allowed to cool a bit. See this Recipe
2. Then you can add the grated cheese and the eggs, which should be at room temperature.
3. Next, use a wooden spoon to vigorously stir the ingredients together to make a thick, custardy sauce.
4. Finally, transfer your just-cooked pasta to the bowl and toss it with the sauce, adding little pasta water as you go, until the sauce is creamy and coats the noodles.
