Bring a large pot of salted water to a boil. Add rigatoni and cook until al dente, about 11 minutes. Drain, reserving 1 cup of pasta water.

Heat olive oil in a large skillet over medium heat. Add onion and sauté until translucent, about 5 minutes.

Add minced garlic and red pepper flakes, cooking for another minute until fragrant.

Stir in tomato paste and cook for 2 minutes, then pour in vodka. Allow to simmer until the alcohol mostly evaporates, about 3 minutes.

Lower the heat and add heavy cream, stirring well. Simmer for 5 minutes until the sauce thickens slightly.

Mix in half of the grated Parmesan cheese and stir until melted and combined.

Add cooked rigatoni to the sauce, tossing to coat. If the sauce is too thick, add reserved pasta water a little at a time until desired consistency is reached.

Season with salt to taste and serve topped with remaining Parmesan and fresh basil leaves.