Bring a large pot of salted water to a boil. Add the pasta and cook until barely tender, about 4 minutes. Drain the pasta, reserving 1 cup of the cooking water, and set aside.
Set a 14-inch saute pan over medium-high heat and add the olive oil. Once the oil is hot, add the onion and cook until lightly caramelized and wilted, 3 to 4 minutes. Add the garlic and saute until fragrant, about 30 seconds. Add the crushed red pepper and saute briefly; then add the tomato sauce and tomato paste. Cook until the sauce has reduced by about 1/2, about 3 minutes. Add the shrimp to the sauce and cook for 2 minutes.
Add the pasta and the reserved cooking water to the pan, and cook until the pasta is heated through and coated with the sauce, 3 minutes. Season the pasta with the salt, and garnish with the parsley. Toss to combine, and serve with the grated cheese, if using and desired.
Recipe copyright Emeril Lagasse, courtesy MSLO, Inc.