In a large dutch oven, heat oil on medium heat. Add in onions and garlic, season with salt and pepper, cook until softened and onions are translucent.
Add in tomato paste and red pepper flakes, and stir to evenly coat onions. Cook for 5 minutes, stirring occasionally
Deglaze pan with vodka sauce, scraping up the browned bits on the bottom of pan.
Add the cream to the pan slowly and stir to fully incorporate until sauce is smooth. Remove from heat so sauce does not burn.
Cook rigatoni per package instructions until al dente.
Add ½ cup of pasta water to sauce and stir in parmesan cheese until sauce is smooth and creamy. Season sauce to taste with salt and pepper. If sauce is too thick, add in more pasta water.
Add pasta to sauce and toss to coat. Serve with parmesan on top and basil leaves if desired. Enjoy!