Puree all the chilies and oil in a blender until smooth. Pour into a small saucepan and bring to a low boil and simmer 1 minute. Remove pan from the heat to cool and infuse the oil.
Pour the mixture through a mesh strainer into a measuring cup. For clearer oil, avoid pressing down on the solids; if the mix starts to move slowly through the strainer, stir gently with a spoon and/or lift out some of the solids. Line the strainer with a piece of cheesecloth and pour the oil through one more time.
Transfer the oil to an airtight jar or bottle; store in a cool, dark place or in the refrigerator for up to 1 month.
To make the pasta
Bring a large pot of water to a boil and add a small handful of salt. Add the spaghetti or pasta of your choice.
Meanwhile, heat the onion, garlic and extra-virgin olive oil in a sauté pan over medium heat until it starts to sizzle; scoop out ½ cup of the boiling pasta water and add to the pan. Cover, lower heat and cook 5 minutes or until the onion and garlic are very tender.
If there’s any water left in the pan, let it bubble away in the uncovered pan until reduced to a tablespoon or so.
Once the pasta is just about done, drain and reserve about ½ cup of the cooking water in a small bowl.
Add the drained pasta to the sauté pan over low heat, along with ½ cup of the cheese; stir enough water to blend with the cheese to coat the pasta.
Serve in bowls drizzled with some parsley, hot chili oil, crushed red pepper and additional cheese to taste.
It's worth making the chili oil separately ahead of time, just to have on hand for that spontaneous midnight craving. Of course, you can make this pasta without it; just add a bigger pinch of crushed red pepper.Inspired by this recipe