Bring a large pot of salted water to a boil. Add the tortellini and cook according to package directions until al dente. Reserve about 1/2 cup of pasta water before draining.

While the tortellini is cooking, cook the diced pancetta in a large skillet over medium heat until crispy and golden brown. Remove the pancetta with a slotted spoon and set aside, leaving the rendered fat in the skillet.

In a medium bowl, whisk together the egg yolks, Pecorino Romano cheese, heavy cream (if using), and black pepper until well combined.

Immediately after draining the tortellini, add it to the skillet with the rendered pancetta fat. Toss to coat. Remove the skillet from the heat.

Slowly drizzle a tablespoon or two of the reserved hot pasta water into the egg mixture, whisking constantly to temper the eggs.

Pour the tempered egg mixture over the tortellini and toss quickly and continuously until the sauce thickens and coats the pasta evenly. Add more pasta water, a tablespoon at a time, if needed to reach the desired consistency. Be careful not to overcook the sauce.

Stir in the crispy pancetta. Taste and adjust seasoning with salt and pepper as needed.

Serve immediately, garnished with chopped fresh parsley, if desired.