Fish Pie

Heat the oven to 400° F and line a large, rimmed sheet pan with parchment paper.

Add the potatoes to a large pot of boiling salted water and cook until tender, about 12 minutes. Drain well and return to the hot pot to ensure all the liquid has evaporated.

While potatoes are cooking, melt the butter in a large nonstick saute pan. Add the leeks and cook over medium-low heat until nicely softened, about 20 minutes. Be sure the leeks don’t brown. Add about ½ cup LEMON BUTTER GARLIC SAUCE and cook, simmering another 5 minutes.

Add 1 cup of the milk, ½ cup of the whipping cream, the mustard and salt to the potatoes and mash or whip until smooth. Stir in 1 cup of the cheese. Set aside.

Add 1 cup of the milk and ½ cup cream to the leek mixture and bring to a boil. Combine the corn starch and the remaining 1/3 cup of milk and whisk together until smooth. Whisk this into the leeks and milk until thickened, about 30 seconds. Still simmering, add the shrimp and fish to the pan and cook, stirring gently so as not to break up the fish. Cook until the shrimp is pink, about 5 minutes. Season with salt and pepper and pour the entire mixture into a large ovenproof casserole dish. Set the dish on the prepared sheet pan.

Spoon the mashed potatoes evenly over top of the fish mixture. Sprinkle with the remaining ½ cup cheese.

Bake in the oven until bubbly and brown, about 45 minutes. Let rest for 15 minutes before serving.