Cook the Pasta: Bring a large pot of salted water to a boil. Cook the pasta according to package instructions until al dente. Drain and set aside, reserving a cup of pasta water.

Prepare the Sauce: In a large skillet, heat the butter and olive oil over medium heat. Add the diced onion and cook for 3-4 minutes, until softened. Stir in the minced garlic and cook for another minute.

Add Tomatoes: Stir in the crushed tomatoes and diced tomatoes (if using fresh tomatoes). Allow to simmer for about 5-7 minutes, letting the tomatoes break down and release their flavor.

Add Cream: Pour in the heavy cream and stir to combine. Let the sauce cook for a couple of minutes until it thickens slightly. Add in the Parmesan cheese and stir until melted and incorporated.

Season the Sauce: Add salt, pepper, and red pepper flakes for a little heat (optional). Taste and adjust the seasonings as needed. If the sauce is too thick, add a little of the reserved pasta water to reach your desired consistency.

Combine Pasta and Sauce: Add the cooked pasta into the skillet and toss to coat with the sauce. Let the pasta sit in the sauce for 1-2 minutes to absorb the flavors.

Finish the Dish: Remove from heat. For extra freshness, sprinkle chopped basil on top and toss one last time.

Serve: Plate the pasta and garnish with more Parmesan cheese and basil. Serve immediately and enjoy!