Bring a large saucepan of lightly salted water to a boil over high heat. Add the angel hair pasta and cook until al dente, 2 to 3 minutes; drain.
Melt the butter in a large frying pan over medium heat. Stir in the garlic, onion, parsley, salt, pepper, Worcestershire sauce, lemon juice and white wine. Once the mixture begins to bubble, increase the heat to medium-high and stir in the prawns. Cook and stir until the prawns turn pink and are no longer transparent in the centre, about 5 minutes.
Serve the scampi over a bed of angel hair pasta. Sprinkle with Pamesan cheese and avocado to serve.