Bring a large pot of salted water to a boil and cook the pasta for 8 to 10 minutes until al dente, then reserve 1/4 cup pasta water and drain.
While the pasta cooks, melt the butter in a large skillet over medium heat for 1 minute.
Add the sliced garlic and red pepper flakes, then cook for 2 minutes, stirring constantly, until the garlic is golden and fragrant.
Add the drained pasta and reserved pasta water to the skillet, toss for 1 minute until the sauce coats the noodles evenly.
Remove from heat, stir in the parmesan cheese and parsley, season with salt and black pepper, and serve immediately.