Bring the broth to a boil in a large pot. Add the pasta to the broth and cook until tender.
In a separate smaller pot, steam the spinach.
When the spinach turns bright green (about 2 minutes), add the spinach and the steaming water to the broth.
Crack the egg into a bowl and beat it with a fork. When the broth is boiling, drizzle the egg slowly into it. Serve immediately.