Fill a large pot with lightly salted water and bring to a rolling boil. Stir in spaghetti and return to a boil. Cook uncovered, stirring occasionally, until tender yet firm to the bite, 9 to 11 minutes. Drain.
Heat olive oil in a deep skillet until hot. Remove from heat and add garlic scapes; let stand for 3 minutes. Mix in parsley. Season with salt and pepper. Serve over drained spaghetti sprinkled with Parmesan cheese.