Start by boiling a large pot of salted water.

Once the pasta is al dente, drain it in a colander and set aside.

In a saucepan, heat the olive oil over medium heat and add the diced onion.

Sauté until translucent, about 3-4 minutes.

Stir in the minced garlic and cook for another minute.

Pour in the heavy cream and bring to a gentle simmer.

Add the grated Parmesan cheese and stir until melted and smooth.

Add the drained pasta to the sauce and toss to coat evenly.

Season with salt and pepper to taste, then garnish with fresh basil if desired.