Bring a large pot of salted water to a boil. Add the rigatoni and cook according to package instructions until al dente, usually about 10-12 minutes. Drain well and set aside.
While the pasta cooks, heat 2 tablespoons of olive oil in a large skillet over medium heat. Add the chopped onion and sauté for about 3-4 minutes until translucent. Stir in the minced garlic and cook for an additional 30 seconds until fragrant.
Add the ground beef to the skillet, breaking it apart with a spatula. Cook until browned and no longer pink, about 6-8 minutes. Season with salt, pepper, and 1 teaspoon of Italian seasoning as it cooks.
Pour in the diced tomatoes (with their juices) and tomato sauce. Stir well to combine. Bring the mixture to a simmer and let it cook for 5-7 minutes, allowing the flavors to meld and the sauce to thicken slightly.
Reduce the heat to low and slowly pour in the heavy cream, stirring constantly to incorporate it evenly into the tomato sauce. Let the sauce simmer gently for another 3-4 minutes until creamy and smooth.
Add the drained rigatoni directly into the skillet with the creamy tomato beef sauce. Toss everything together until the pasta is fully coated in the sauce.
Sprinkle shredded mozzarella cheese over the pasta. Cover the skillet with a lid and let it sit for 2-3 minutes off the heat until the cheese melts into a gooey, delicious topping.
Serve the Creamy Tomato Beef Rigatoni hot, garnished with fresh basil leaves. This final touch adds a burst of color and fresh herbal flavor that complements the rich sauce beautifully.