Cook the noodles like you normally would - according to the package directions - when the noodles are about halfway cooked, crack in the egg and poach it in the broth over low heat, basting with broth or covering with a lid briefly to help it cook through.
Carefully pour the lot into a bowl, add the butter and any veggies you like, and immediately top with the cheese slices. Sprinkle with sesame seeds, green onion and Sriracha to taste and serve immediately.
