Cook the bow tie pasta according to package instructions in a large pot of salted boiling water. Drain and set aside.

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

Add the diced onion and bell pepper to the skillet. Sauté for about 3-4 minutes until the vegetables are tender.

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

Add the diced tomatoes (with their juice), Italian seasoning, salt, and pepper. Bring the mixture to a simmer and cook for about 5 minutes.

Combine the cooked bow tie pasta with the sausage mixture, tossing to coat evenly.

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