Cook the pasta in boiling salted water, according to pack instructions, until al-dente, then drain and retain a few tablespoons of the cooking liquid.
Place the butter in a frying pan over a medium heat and cook until brown and nutty.
Add the chilli, garlic, lemon zest, prawns and cook for 2 minutes, add the crab meat and continue to cook for another two minutes.
Transfer the cooked pasta to the pan and add a tablespoon of the reserved cooking liquid and stir well. If the pasta looks a little dry add another tablespoon of cooking liquid. Toss everything together until evenly combined then add a squeeze of lemon juice and season to taste.
Transfer to bowls and garnish with chopped parsley and a lemon wedge, serve immediately