Bring a large pot of water to a boil, then add the pasta. Follow the instructions on the pasta package to boil your noodles until they’re just shy of al dente – around 2 minutes less than what the package says. Then, drain the pasta from the water, reserving 1 cup of the pasta water for later (which will be used for the sauce).
Add the butter and olive oil to a large saucepan and cook until the butter is melted.
Once the pan is hot, add the onions and garlic and cook until fragrant and the onions are soft but not browned.
Then, add the tomatoes and continue cooking until the tomatoes are softened, stirring frequently.
Season with salt and pepper, then stir in the tomato puree and heavy cream.
Allow the sauce to simmer for a few more minutes until it’s thickened, then stir in the vodka, pepper flakes, basil, and half of the pasta water (more if you prefer sauce thinner).
Continue simmering the sauce for 2 to 3 minutes over low heat, and transfer the sauce to a blender and blend until smooth.
After blending the sauce, clean the saucepan and pour in the finished sauce and cooked pasta. Cook over medium low heat for 2 to 3 minutes, gently stirring the pasta into the sauce as you cook.
Serve warm with Parmesan cheese sprinkled on top.