Prawn thermidor recipe

Ingredients

• 4 pieces black tiger prawns, large, butterflied
• 1/4 cup butter
• 1/4 cup onion, minced
• 1/4 cup button mushrooms, sliced
• 1 tablespoon parsley, chopped
• salt and pepper, to taste
• SAUCE
• 2 tablespoons butter
• 2 tablespoons all-purpose flour
• 1/2 cup Evaporated nilk
• 2 tablespoons liquid cream
• A pinch of nutmeg
• salt and pepper
• 1/4 cup bread crumbs
• 2 tablespoons parmesan cheese, freshly grated