Combine parsley, butter, garlic, salt, juice of half a lemon, and pepper in a blender. Blend until smooth.
Pound the chicken to about 1 inch thick. Brush each piece with garlic butter (reserve some for the pasta). Refrigerate for 30–40 minutes while you prep the other ingredients.
Mix breadcrumbs with spices in a shallow dish. Place flour in another dish and beaten eggs in a third.
Heat oil in a pan over medium heat. Dip each chicken breast in eggs, then flour, then eggs again, then breadcrumbs. Fry until golden and crispy.
Boil a pot of water with salt and a little olive oil. Cook spaghetti according to package directions. Drain and toss with the remaining garlic butter and mozzarella.
Arrange spaghetti in a large bowl, top with crispy chicken, and sprinkle with extra parsley and lemon.