Boil a large pot of salted water. Add pasta and cook according to package directions until al dente, about 8-10 minutes. Reserve 1 cup of pasta water, then drain and set aside.

In a large skillet, melt 2 tbsp of butter over medium heat. Add chopped onion and minced garlic, sauté for 2-3 minutes until onion is translucent.

Stir in 1 tbsp of tomato paste and cook for 1 minute to let flavors meld.

Lower heat, add 2 cups of tomato sauce and ½ cup of heavy cream. Stir and let simmer for about 5 minutes until slightly thickened.

Toss the drained pasta into the skillet until coated in sauce. Use reserved pasta water to adjust sauce thickness if needed.

Mix in shredded parmesan cheese until melted. Serve immediately, garnished with parsley or cilantro.

For optional shrimp, sauté shrimp with minced garlic and a splash of fish sauce for 3-4 minutes before folding into the pasta.