Remove meat from crabs, discard shell fragments, and wash the empty shells.
Mash meat with seasoning and spoon it back into the clean shells.
Melt cheese and milk in a saucepan, then stir in breadcrumbs and flour for 3 minutes.
Whisk Worcestershire sauce, eggs, and mustard into the cooled cheese mixture.
Preheat the deep-fat fryer to 180°C.
Fry potatoes for 3 minutes until golden, then drain and season.
Preheat the grill to high.
Top crab shells with sauce and melted butter, then grill until bubbling.
Dress the lettuce leaves with olive oil and lemon juice.
Serve the grilled crab in shells with the fries and salad.