Start by boiling water in a large pot and cook the pasta according to package instructions.
While the pasta cooks, heat olive oil in a large skillet over medium heat.
Add chopped onion and minced garlic; sauté until translucent.
Slice the sausage and add it to the skillet, cooking until browned.
Pour in the canned diced tomatoes, including the juice, and stir well.
Let the mixture simmer for 5 minutes to meld the flavors.
Stir in the heavy cream and season with salt and pepper.
Once the pasta is al dente, drain it and add it to the skillet.
Gently toss the pasta with the sauce until well coated.
Serve hot, garnished with fresh basil and grated Parmesan cheese.