Fish Pie 1 : Peel potatoes and bake until it's cooked 2 : Mash it up and lay it out onto a baking tin 3 : Mix tuna fish with 1/2 can of mushroom cream and 1/2 Cup of mayonnaise 4 : Mix well then top up on potato mash with cheese and bake for 10 mins Than you will be ready to have your meal.