Parmesan-Crusted Cod Skillet with Garlic Spinach in 30 Minutes Step-by-step instructions

Before you start

Start by taking the cod out of the refrigerator only when you are ready to cook, since raw fish should not sit at room temperature for more than 30 minutes. Pat the fillets dry with paper towels, then season both sides with kosher salt and black pepper.

Mince the garlic, chop the parsley, slice the lemon into wedges and grate the Parmesan on a box grater until you have a fine heap of shreds. Set the breadcrumbs and Parmesan in a small bowl and add the minced garlic to them so the topping is ready to spoon over the fish. Having everything within reach keeps the butter from browning before the fish goes in.

Instructions

Build the garlic spinach base

1. 1Prepare the cod and garnishes
   Keep the cod refrigerated until just before cooking, then pat the fillets dry with paper towels and season both sides with salt and pepper. Mince the garlic with a chef's knife, chop the parsley, and cut the lemon into wedges. Grate the Parmesan on a box grater until you have a fine heap of shreds.
   Look for Fillets are dry to the touch and the Parmesan forms a fine, fluffy pile.
   Tip Dry fillets brown far better, so blot them well before seasoning.
2. 2Melt butter and wilt spinach
   Place a 12-inch cast iron skillet over medium heat and melt the butter until it foams. Arrange the baby spinach leaves in the skillet around the space where the cod will sit, and let them wilt for about one minute, turning them gently with tongs.
   Look for Butter foams, then the spinach turns bright green and shrinks.
   Tip Wilt the spinach in the pan while the butter is still foaming for even color.

At the end of this phase, the butter should be foaming and the baby spinach should be bright green, shrunken and glossy in the skillet. The leaves should still hold a little shape rather than turning mushy. Check that the spinach is spread around the center of the pan, leaving a clear spot for the cod. The smell should be buttery with a hint of garlic. If the spinach is still raw in the middle, give it another 30 seconds of stirring before you move on to the fish, so the base is ready to hold the fillets.

Top and sear the cod

3. 3Top the cod with crust
   Mix the Parmesan, breadcrumbs, and minced garlic in a small bowl. Place the cod fillets in the skillet on top of the spinach and spoon the crumb and garlic mixture over the fish, pressing it lightly so it adheres.
   Look for Topping covers the fish evenly and clings to the surface.
   Tip Press the topping gently so it does not slide off during cooking.
4. 4Cook and flip the cod
   Cook over medium heat for about 4 minutes, until the bottom crust turns golden. Slide a thin spatula under the fillet and flip it with tongs, letting it sizzle in the melted butter for another 4 to 5 minutes, until the crust is deep golden brown.
   Look for Crust turns deep golden and the butter sizzles around the fish.
   Safe temperature 145°F (63°C) internal temperature (fish)
   Tip Baste the fillet with the butter now and then to brown the crust evenly.

Once the topping is spooned over the fish and the first side has browned, the crumbs should look golden on the surface and cling firmly to the flesh. The butter should be sizzling steadily around the fillet without smoking.

Lift a corner with a spatula to check the underside: it should be pale golden and set enough to turn. If it sticks or the topping is falling away, let it cook another minute before attempting the flip. Keep the heat at medium so the crust browns without burning on the bottom of the pan.

Flip, finish and serve

5. 5Check the fish and finish
   Check that the cod flakes easily with a fork and the flesh is opaque all the way through, reaching 145°F (63°C) at the thickest part. Remove the skillet from the heat, scatter the chopped parsley over the spinach and fish, and serve with lemon wedges.
   Look for Cod flakes easily and looks opaque right through the center.
   Safe temperature 145°F (63°C) internal temperature (fish)
   Tip Squeeze lemon over the fish just before eating to keep the crust crisp.

When the fillet has been flipped and cooked on the second side, the crust should be deep golden brown all over, with crisp edges. The cod should flake easily with a fork and look opaque through the center. Check the thickest part of the fillet with an instant-read thermometer, aiming for 145°F (63°C). The spinach should be tender and glossy under the fish. Remove the skillet from the heat, scatter parsley over the top, and bring it to the table with lemon wedges while the crust is still crisp.

Common mistakes

The most common mistake is cooking the fish over heat that is too high. The Parmesan and butter brown quickly, so the crust can darken and burn before the center of the cod turns opaque. Keep the skillet at medium and watch the color closely, especially after the flip.

Another common error is skipping the drying step: wet fillets release moisture into the pan and steam the crust instead of crisping it. Finally, do not crowd the skillet with extra fillets, because the spinach and fish will steam rather than brown. If the topping slides off, the fish was probably too wet or was flipped too early, so pat it dry and let the first side set before lifting.

How to tell it’s done

Cod is done when the flesh has turned from translucent to opaque all the way through and separates into flakes when pressed gently with a fork. The crust should be deep golden brown and firm to the touch. For certainty, use an instant-read thermometer inserted into the thickest part of the fillet: it should read 145°F (63°C).

Do not leave the fish in the pan after it reaches this point, since the flesh will become dry and tough within a minute or two. If the fish is still glossy and translucent in the center, return it to the medium heat for another minute, then check again. A properly cooked fillet should feel tender and moist, not firm or rubbery.

• Fish: 145°F (63°C) in the thickest part