Cook the bow tie pasta according to package instructions until al dente. Drain and set aside.

In a large skillet, heat the olive oil over medium heat. Add the Italian sausage, breaking it apart with a spoon, and cook until browned and cooked through, about 5-7 minutes.

Add the chopped onion to the skillet and sauté for about 3-4 minutes until softened. Stir in the minced garlic and cook for an additional 1 minute until fragrant.

Pour in the diced tomatoes (with juices) and heavy cream. Stir to combine and bring to a simmer.

Add the Italian seasoning, salt, and pepper. Let the sauce simmer for about 5 minutes, stirring occasionally.

Stir in the cooked bow tie pasta and half of the Parmesan cheese until well combined. Cook for an additional 2-3 minutes until heated through.

Serve hot, topped with the remaining Parmesan cheese and fresh basil leaves if desired.