Boil your water and salt the water when it starts to boil. Cook the pasta according to the package instructions. Make sure to reserve ¼ cup of the pasta water to add to the dish later.
Dice your onion and mince your garlic. While the pasta cooks, in a large skillet, over medium high heat, add the olive oil and butter until the butter melts. Once melted, add the onion and garlic.
Cook the onion and garlic until fragrant (about 2 minutes). Then stir in the tomato paste and cook this for an additional 3 minutes until the tomato paste caramelizes.
Add in the salt and red pepper flakes and stir to combine. Pour in your heavy cream and stir until this mixture comes together. Add the cream in slowly to make sure it is the consistency that you like.
Once the pasta is done cooking, add in your pasta and the reserved pasta water. Again, stir this until fully combined. Plate this and top with your desired amount of parmesan - enjoy!
