Fish pie is a yummy dish that has fish in it! First, we need to cook the fish (like cod or salmon) by boiling it in water until it turns white and flaky. Then, we mix the fish with creamy sauce (like milk and butter) and some other ingredients like potatoes, carrots, peas, and onions. It's like making a sandwich, but instead of bread, we use mashed potatoes on the bottom and top of the dish. Finally, we put the mixture into a baking dish and bake it in the oven until it's all hot and bubbly. Then, we can eat it with a spoon and it will taste delicious!