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 chopped onion and sauté for about 3-4 minutes until translucent.

Add the minced garlic and cook for an additional 1 minute until fragrant.

Remove the casing from the Italian sausage and add it to the skillet. Cook until browned, breaking it up with a spoon, about 5-7 minutes.

Stir in the diced tomatoes (with juice), heavy cream, Italian seasoning, salt, and pepper. Bring to a simmer and cook for 5 minutes until slightly thickened.

Add the cooked bow tie pasta to the skillet and toss to combine everything evenly. Stir in the grated Parmesan cheese until melted and creamy.

Serve immediately, garnished with fresh basil leaves if desired.