Ingredients
3 russet potatoes, peeled and cut into chunks
3 tablespoons butter
1 pinch freshly grated nutmeg
salt and black pepper to taste
1 pinch cayenne pepper, or to taste
1/2 cup milk
Spinach
2 teaspoons olive oil
12 ounces baby spinach leaves
Sauce:
3 tablespoons butter
3 tablespoons all-purpose flour
2 cloves garlic, minced
2 cups cold milk, divided
2 teaspoons lemon zest
Cod
1 tablespoon butter
salt and black pepper to taste
1 pinch cayenne pepper, or to taste
2 pounds boneless cod fillets
1/2 lemon, juiced
chopped fresh chives for garnish
Preparation
Bring a large saucepan of salted water and to a boil; add russet potatoes to boiling water and cook until very tender, about 20 minutes. Drain well. Mash in 3 tablespoons butter until thoroughly combined. Season with nutmeg, salt, black pepper, and cayenne pepper to taste. Mash 1/2 cup milk into potato mixture until smooth. *
Drizzle olive oil in a large Dutch oven over medium-high heat, add spinach, and season with a big pinch of salt. Cook, stirring occasionally, until spinach has wilted, about 1 minute. Transfer to a bowl lined with paper towels to wick away excess moisture.
Heat 3 tablespoons butter and flour in a saucepan over medium heat; whisk mixture to a smooth paste. Cook, stirring constantly, until mixture has a nutty smell and is slightly browned, about 2 minutes. Add chopped garlic; whisk until fragrant, 10 to 20 seconds.
Whisk 1 cup cold milk into flour mixture; cook until thickened. Whisk in remaining 1 cup milk and lemon zest. Bring white sauce to a gentle simmer, whisking constantly; season with salt. Turn heat to very low and keep sauce warm.
Preheat oven to 375 degrees F (190 degrees C). Grease an 8x12-inch casserole dish with 1 tablespoon butter.
Season buttered pan with salt, black pepper, and cayenne pepper. Lay boneless cod fillets into the pan in a single layer. Season tops of fillets with more salt, black pepper, and cayenne pepper. Spread spinach evenly over fish and drizzle with lemon juice. Spoon white sauce over spinach; give casserole dish several taps and shakes to eliminate bubbles.
Drop mashed potatoes by heaping spoonfuls over the casserole and spread smoothly to cover. Place dish onto a rimmed baking sheet to catch spills.
Bake in the pre-heated oven until bubbling, about 40 minutes. Turn on oven's broiler and broil until potato crust has a golden brown top, about 2 minutes. Fish should flake easily. Let stand 10 minutes before serving. Garnish with a sprinkle of chives.
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* Leftover mashed potatoes work just fine
This produces a relatively thin sauce. If you like it thicker then just increase the flour and butter in the sauce
If everything is hot then decrease the cooking time to 30 minutes
While not the best leftover dish it does transform nicely into a potato soup.