Using http://www.livejournal.com/users/whipartist/123717.html as a base recipe, I replaced the cheddar with half gruyere and half fontina, plus a couple ounces of parmesan. While the water was boiling for the pasta, I chopped up some pancetta and cooked it 'til it was crisp.
When I addeded the pasta to the sauce I also tossed in the pancetta.
It turned out pretty tasty, though next time I'll either use more pancetta or leave it out entirely. I wound up using about 3oz, since that's what I had around, but it wasn't enough... I suspect twice that would be a good minimum.