Preheat the oven to 220°C and bake pricked potatoes for 45 minutes.
Clean scallops, then warm their trimmings in the fish stock and set aside.
Dry four deep shells in the oven for 2 minutes and place them on salt mounds on a tray.
Rice the potato flesh, beat with egg yolks and 25g butter, then pipe onto shell edges.
Melt 50g butter and whisk in flour for 2 minutes to create a roux.
Whisk sieved stock and cream into roux, simmer for 2 minutes, then stir in chervil.
Sear seasoned scallops in 50g butter for about 1 minute per side until golden.
Fry the shallot, courgette, carrot, and leek in butter until tender.
Layer vegetables and scallops in shells, top with sauce, cheese, and breadcrumbs.
Grill the shells for 1-2 minutes until the sauce is glazed and potato is golden.
Blend salad dressing ingredients, toss with lettuce and chives, and serve with the shells.