• 4 fresh trout, filleted
• ¼ pint dry white wine
• ¼ pint water
• salt and freshly ground black pepper
• butter
• 8 button mushrooms, quartered
• ¼ pound frozen prawns
• ¼ pint double cream
• 2 egg yolks
• 4 tablespoons freshly grated gruyère

Poach trout fillets in a court-bouillon made of equal parts dry white wine and water, and seasoned to taste with salt and freshly ground black pepper.

Transfer fillets to a well-buttered ovenproof dish and keep warm. Add 4 tablespoons butter, quartered mushrooms and half the prawns to the sauce, and bring to a boil. Cook over a high heat until sauce is reduced to half the original quantity. Remove from heat.

Combine double cream and egg yolks in a small bowl; stir in a little of the hot sauce; then pour egg and cream mixture into hot sauce and cook over a medium heat, stirring constantly, until mixture thickens. Do not let it come to a boil, or eggs will curdle.

Pour sauce over trout fillets; sprinkle with freshly grated Gruyère and glaze under preheated grill until sauce is bubbly and golden.