White Fish Pie

1 . Stage

Preheat the oven to 350 degrees F (175 degrees C). Spray a casserole dish with cooking spray.

2 . Stage

Melt 1 tablespoon butter in a large skillet over medium heat. Add milk and lay fish in the milk to poach. Sprinkle with thyme, sea salt, and pepper. Cover the pan and bring milk to very low boil. Cook until fish flakes easily with a fork, about 7 minutes.

3 . Stage

Remove fish to plate and use a fork to break up into bite-sized chunks. Pour milk into a bowl and set aside.

4 . Stage

Melt 1 tablespoon butter in the skillet over medium heat. Add onion, celery, and carrot and saute until soft, about 5 minutes. Add garlic and saute until fragrant, about 1 minute. Turn heat to low and scrape the veggies to the side of the skillet. Add the remaining 2 tablespoons of butter and lemon juice to the empty spot. Sprinkle flour over the melted butter; whisk and cook until it forms a thick, golden paste, 10 to 15 minutes.

5 . Stage

Combine the veggies back in with the roux. Add the milk and fish back to the skillet. Gently toss together. Remove from heat.

6 . Stage

Add 1/2 of the fish mixture to the prepared casserole dish, then top with 2 cups of the mashed potatoes. Repeat the layers once more. Sprinkle the top of the casserole with Cheddar cheese.

7 . Stage

Bake in the preheated oven until cheese is golden brown, about 35 minutes.