Boil the Pasta: Bring a large pot of salted water to a boil. Add the penne pasta and cook until al dente, about 8-10 minutes. Reserve 1 cup of pasta water and drain the rest.

Brown the Sausage: In a skillet, heat olive oil over medium-high heat. Add the sausage, breaking it apart, and cook for 5-7 minutes until browned.

Sauté Aromatics: Add chopped onion and sauté for 3-4 minutes until translucent. Then add minced garlic for another 30 seconds.

Build the Sauce: Stir in tomato paste and cook for 1-2 minutes, then add crushed tomatoes, Italian seasoning, red pepper flakes, salt, and pepper. Simmer for 4-5 minutes.

Create the Creamy Base: Reduce heat to low, add heavy cream, and stir until smooth. Mix in Parmesan cheese until fully combined.

Combine the Pasta and Sauce: Toss the cooked pasta with the sauce, adding reserved pasta water if needed to adjust consistency.

Finish and Serve: Adjust seasoning as needed. Stir in fresh parsley or basil before serving, and enjoy your pasta hot.