To a large pot with boiling water, add some salt (about 1 tbsp of kosher salt) and the pasta, making sure the water covers the pasta by at least 1 inch. Boil the pasta for the time indicated on the package minus 1 minute. Stir a few times to make sure the pasta doesn't stick. When you drain the pasta once it's cooked, reserve 1 cup of pasta water.
While the pasta cooks, work on the sauce. To a skillet or pan, add 1 tbsp of olive oil, diced chorizo, and minced onion with a pinch of salt. Cook for about 5-6 minutes on medium-high until the red onion has softened.
Add the cream and 1 cup of pasta water to the sauce. Bring to a simmer for 1-2 minutes. Add the parmesan, stirring it in for a few seconds.
Combine the cooked and drained pasta with the sauce. Put the pot back on heat for 1-2 minutes, stirring until the pasta is coated in the sauce.
Add fresh basil and a pinch of chili flakes. Taste everything once combined and add salt & pepper to taste.