Bring a large stock pot of salty water to a boil. (Note: This water should taste like the ocean.) Add pasta and cook until it’s a minute away from being al dente.
While the pasta is cooking, add your olive oil and garlic to a cast-iron skillet. Cook gently over a medium-low heat until the garlic becomes very fragrant, translucent, and lightly golden, but not browned.
Then, add your crushed red pepper flakes.
Once pasta is ready, remove it from the pot using tongs (reserving the pasta water) and add it to the garlic and oil mixture.
Toss to combine. After a few tosses, you will begin to see your pasta absorb the oil and tighten up.
Once you reach this stage, add a small ladle full of the starchy pasta water until your garlic and oil mixture begin to emulsify into a sauce. If you like your Aglio e Olio a bit looser, add more pasta water.
Once you’ve reached your desired consistency, check for seasoning. Once the taste is to your liking, add parsley, and toss to combine.
Add a splash of lemon juice (optional), and serve immediately.
