Cook the 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 diced onion and sauté for about 5 minutes until softened.
Stir in the minced garlic and cook for an additional minute until fragrant.
Add the chopped roasted red peppers to the skillet and cook for 2-3 minutes, stirring occasionally.
Pour in the heavy cream and sprinkle in the Italian seasoning. Stir well to combine and let it simmer for about 5 minutes, allowing the sauce to thicken slightly.
Season the sauce with salt and pepper to taste. Remove from heat and stir in the grated Parmesan cheese until melted and smooth.
Toss the cooked pasta in the sauce until well coated. Serve immediately, garnished with fresh basil leaves if desired.