Creamy Cod and Potato Gratin
Description
Fresh cod is baked in a bright, herbaceous sauce on top of mashed potatoes in Chef John's fancier gratin version of classic creamed cod.
Ingredients
•
2 medium russet potatoes, peeled and quartered
•
2 (6 ounce) fillets cod
•
2 pinches cayenne pepper, divided, or to taste
•
salt to taste
•
7 tablespoons unsalted butter, divided
•
2 tablespoons finely chopped shallot
•
1 cup heavy cream
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2 teaspoons lemon zest
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1 tablespoon fresh lemon juice
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1 tablespoon chopped fresh tarragon
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2 teaspoons freshly grated Parmigiano-Reggiano, or to taste
Directions
1
Place potatoes in a large pot of well-salted water and bring to a boil over high heat. Reduce heat and simmer gently until tender, about 20 minutes.
2
While potatoes simmer, trim, bone, and cut the cod fillets across into 2-inch pieces.
3
Drain potatoes well and return to the pot. Add a pinch of cayenne, salt, and 4 tablespoons butter. Mash until smooth.
4
Preheat the oven to 450 degrees F (230 degrees C). Grease 2 individual-sized casserole or baking dishes with 1 tablespoon butter. Place both dishes on a baking sheet.
5
Transfer about 2/3 cup of the mashed potatoes into each of the prepared dishes. Smooth out evenly and make a shallow depression with a spoon down the middle. Set aside.
6
Heat remaining 2 tablespoons butter in a deep 10-inch skillet over medium-high heat. Cook the shallots in the hot butter with a pinch of salt until they just start to turn golden, 3 to 4 minutes. Add cream, lemon zest, and a pinch of cayenne, and bring to a simmer. Add cod and wait for the sauce to come back to a simmer. Cook for 1 minute, while basting with the sauce; turn and cook for 1 minute more.
7
Pour in lemon juice and turn off the heat; stir for about 30 seconds.
8
Divide the pieces of cod over the potato. Add enough sauce to just cover the fish and return the pan to the stove.
9
Bring sauce to a boil over medium-high heat and cook until the sauce reduces and thickens, 1 to 2 minutes. Turn off the heat and stir in tarragon.
10
Spoon the thickened sauce over the cod. Add a light dusting of Parmigiano-Reggiano cheese.
11
Bake in the center of the preheated oven until cod is cooked through and the sauce is browned and bubbling, 10 to 15 minutes. Let rest for 5 minutes before serving.