Cook the Pasta - Bring a large pot of salted water to a boil. Cook the pasta according to package instructions until al dente. Reserve 1 cup of pasta water, then drain the pasta and set aside.
Cook the Pancetta - In a large skillet or sauté pan, cook the diced (or cubed) pancetta over medium heat until crispy, about 5-7 minutes but can take longer if heat is lower. Use a slotted spoon to remove the pancetta, leaving the rendered fat in the pan. Set the pancetta aside.
Prepare the Alfredo Sauce - Reduce the heat to medium-low. Add the butter to the same pan with the pancetta fat and let it melt. Stir in the minced garlic and sauté until fragrant, about 1 minute (do not let it brown).Pour in the heavy cream, stirring to combine. Let the cream simmer gently for 2-3 minutes. Gradually whisk in the Parmesan cheese until melted and smooth. Add the black pepper and adjust salt to taste.
Combine Ingredients - Add the peas and cooked pancetta to the Alfredo sauce. Stir to coat everything evenly.Add the cooked pasta to the pan, tossing to combine. If the sauce is too thick, gradually add the reserved pasta water, a few tablespoons at a time, until you reach the desired consistency.
Serve and Garnish - Serve the pasta immediately, garnished with chopped parsley and extra Parmesan cheese, if desired.
