Heat the oil in a frying pan on the hob and gently fry the sliced spring onions for 2 minutes. Stir in the garlic and chilli, then tip the contents of the pan into a bowl. Leave to cool.
Add the crabmeat, ketchup, mayonnaise, Worcestershire sauce and 50 g (2 oz) of the breadcrumbs to the bowl, season with a little salt and pepper and stir well to mix. Shape the mixture into 12 cakes.
Season the flour with salt and pepper on a plate. Beat the egg on a second plate and scatter the remaining breadcrumbs on a third. Dust the fishcakes with the flour, then coat in the egg and breadcrumbs.
Drizzle a little extra oil into a shallow roasting tin and space the fishcakes slightly apart in the tin. (You may need to cook them in 2 batches.) Drizzle with more oil and place on the upper rack of the halogen oven.
Set the temperature to 200°C (392°F) and cook the fishcakes for 8–10 minutes, turning over halfway through cooking. Serve with extra mayonnaise or sweet chilli sauce, scattered with spring onion curls.