Bring a large pot of salted water to a boil. Cook pasta according to package instructions until al dente. Reserve 1 cup of pasta water, then drain and set pasta aside.

If using shrimp, season lightly with salt and pepper. In a large skillet over medium-high heat, melt 1 tablespoon butter. Add the shrimp in a single layer and cook for 1–2 minutes per side until they turn pink and opaque. Remove and set aside.

In the same skillet, melt the remaining butter. Add minced onion and garlic and sauté until fragrant and translucent. Stir in the tomato paste and cook for 1–2 minutes to deepen the flavor. Sprinkle in oregano and a pinch of salt, mixing well.

Reduce heat to medium-low. Pour in the tomato sauce, heavy cream, and Italian seasoning. Stir until the sauce turns a soft pink and thickens slightly. Let it simmer for 3–5 minutes. If it becomes too thick, loosen with a splash of reserved pasta water.

Add the cooked pasta to the skillet, tossing gently to coat each strand in the sauce. Return the shrimp to the pan, mixing them through the pasta. Add red pepper flakes for a touch of spice. Sprinkle generously with shredded Parmesan cheese, stirring until melted and creamy.

Serve hot, garnished with freshly chopped cilantro or parsley. A final dusting of Parmesan and a drizzle of olive oil make it restaurant-worthy.