Heat the olive oil in a large skillet over medium heat. Add the onion and garlic, and cook until softened. Add the mushrooms and cook for an additional few minutes.
Stir in the flour and cook for another minute. Add the fish stock or white wine and bring to a simmer. Add the peas, thyme, and black pepper. Add the cooked fish and stir to combine.
Melt the butter in a saucepan over medium heat. Stir in the flour and cook for a few minutes. Gradually add the milk, stirring constantly. Cook until thickened. Add the cheese and stir until melted.
Spread the fish mixture into an 8x12 inch baking dish. Spread the mashed potatoes over the top. Pour the cheese sauce over the potatoes. Bake in preheated oven for 30 minutes, or until potatoes are golden.
Interesting Facts
Fisherman's pie is also known as “cottage pie”.
This dish is said to have originated during the Napoleonic wars of the 19th century.
Fisherman’s pie is a popular dish in British pubs.
It can be made with any type of fish, such as salmon, cod, or haddock.