Cook the penne pasta according to package instructions until al dente. Drain and set aside.
In a large skillet over medium heat, add the olive oil. Once hot, add the diced onion and red bell pepper. Sauté for about 5 minutes until softened.
Remove the casing from the Italian sausage and crumble it into the skillet. Cook until browned and cooked through, about 7-10 minutes.
Stir in the minced garlic and cook for an additional minute until fragrant.
Add the diced tomatoes (with their juice), oregano, basil, salt, and pepper. Bring to a simmer and let cook for 5 minutes.
Reduce the heat to low and stir in the heavy cream and Parmesan cheese. Mix until the cheese is melted and the sauce is creamy.
Add the cooked penne pasta to the skillet and toss to coat in the sauce. Cook for another 2-3 minutes to heat through.
Serve immediately, garnished with fresh basil leaves if desired.