Cook spaghetti in boiling salted water for 8-10 minutes. In the meantime, wash chicken fillet, dab dry and season with salt and pepper. Heat some oil in a frying pan and fry the chicken fillet on both sides for 5 minutes on medium heat until golden brown.
Wash the lemon, peel thinly and cut into strips. Halve the lemon and squeeze. Wash parsley, dab dry, pluck leaves from the stalks and chop finely. Peel garlic and cut into thin slices.
Remove the chicken filet from the pan and keep warm. Add the remaining olive oil to the frying fat. Sweat garlic and lemon strips briefly and deglaze with lemon juice. Drain the spaghetti and add to the sauce with the parsley.
Cut the chicken filet into slices and arrange on a plate with the noodles and serve. Garnish as desired with parsley and a lemon wedge.