Bring a large pot of salted water to a boil and cook the 20 oz of cheese tortellini according to package directions until just al dente. Drain and set aside, reserving ½ cup of pasta water.

In a large skillet over medium heat, melt 2 tablespoons butter. Add the diced onion and cook 4–5 minutes until softened and lightly golden. Stir in the 5 cloves minced garlic and cook for another 30 seconds, just until fragrant.

Stir in the 12 oz can of drained diced tomatoes and cook 2–3 minutes, letting the flavors blend and some of the liquid reduce.

Lower the heat slightly and add the 1 cup heavy cream, 8 oz cream cheese, and ½ cup grated Parmesan cheese. Stir continuously until the cheeses melt and the sauce becomes smooth and creamy.

Add 1 teaspoon Italian seasoning, ½ teaspoon crushed red pepper flakes (if using), and season with salt and freshly ground black pepper to taste. Simmer gently for 3–5 minutes until the sauce thickens slightly.

Add the cooked tortellini to the skillet, tossing to coat evenly in the sauce. If the sauce seems too thick, add a few tablespoons of the reserved pasta water to loosen it to your desired consistency.

Spoon into bowls and garnish with chopped fresh basil or parsley and extra Parmesan if desired. Serve hot.