In a large pot of boiling salted water, cooking fettuccine until al dente. Reserve 3/4 cup of salty pasta water and drain.
Place empty pot over medium heat with olive oil, garlic and crushed red pepper flakes. When garlic starts to turn golden, add in cooked pasta, pasta water and parmigiana.
Reduce heat to low, toss pasta until sauce comes together and coats each noodle.
Finish with lemon juice, parsley and black pepper.