This makes enough for four people, more if you have side dishes/bread/whatever. For the cheeses, I'm using homemade manchego and parmesan. The manchego has proven to be a fantastic grating cheese. I'm using spaghettoni instead of spaghetti, it's a little bit thicker and holds up to the really rich sauce better.
Cube the pancetta, roughly half-inch pieces.
Throw into a hot skillet to get some good carmelization, then turn the heat down after a few minutes to do a slow render. We want a bunch of fat to come out.
50/50 mix of the cheeses, grated fine.
Ready to start building the sauce, note the rendered fat.
I didn't get enough pics of this, probably because I was too busy whisking like a crazy person. The bowl is over a big pot with a few inches of boiling water- you want to warm this, not cook it. Otherwise you end up with scrambled eggs and clumps of cheese. Slowly drizzle in about a quarter-cup of the rendered fat, whisking furiously to emulsify it with the eggs. Add in the cheese, continue whisking. It may look a little clumpy at first, but if you apply enough whisk, it smooths out.
Add in the pancetta and the cooked pasta, along with a little bit of the pasta water if you need to loosen it up some. Top with black pepper.