Bring a large pot of salted water to a boil and cook the pasta al dente according to package instructions. Save 1 cup of pasta water.
Heat olive oil in large pan over medium heat and add shallots, cooking for 1-2 minutes or until translucent. Add the sausage and pancetta, cooking another 5-6 minutes, breaking up the sausage.
Add the cherry tomatoes, cooking for about 10 minutes or until thickened. Salt to taste.
While the sauce is simmering, beat the egg yolks and the Pecorino Romano together in a bowl until a thick paste forms. Add ¼ cup of the pasta water and stir until combined. Set aside.
Add the pasta to the sauce as well as ½ cup of reserved pasta water, tossing to combine. Remove from heat and stir in the egg yolk mixture, tossing quickly for 30 seconds. Add more pasta water if needed. Serve with more grated cheese.
Notes
Make sure the water you are cooking the pasta in is salted as some of the flavor comes from it.
DO NOT overcook the pasta when boiling. You want it just al dente or slightly under. It continues to cook with the sauce.
Don't use pre-shredded cheese. You want if finely grated so it melts well. Pre-shredded has added ingredients that will just make it clump up.
Rather than just pouring the sauce over the pasta, toss the pasta directly into the saucepan with the sauce. This helps the pasta get fully coated with the delicious flavors.