Butter-Basted Parmesan Cod with Wilted Spinach Step-by-step instructions

Before you start

Before you start, set out all your ingredients. Slice the lemon into thin wheels, mince the garlic, and mince the parsley. Grate the parmesan cheese and divide it into 3/4 cup for the crust and 1/4 cup for finishing.

Pat the cod loins dry with paper towels. Have your cast iron skillet and fish spatula ready. Because the cooking goes quickly, having everything prepped and within reach makes the process smooth.

Instructions

Prep and Coat

1. 1Prep the lemon, garlic, parsley, and cheese
   Slice the lemon into thin wheels and set aside. Mince the garlic and parsley. Grate the Parmigiano-Reggiano on the fine holes of a box grater. Divide the grated cheese: about 3/4 cup for the crust and 1/4 cup for finishing.
   Look for The lemon wheels are even, the garlic is fine, and the cheese is fluffy and dry.
   Tip Grate the cheese fresh — pre-grated won't melt as smoothly or crust as well.
2. 2Coat the cod in parmesan herb crumbs
   Pat the cod loins dry with paper towels. Season both sides with kosher salt and black pepper. Press each loin into the reserved 3/4 cup of grated parmesan mixed with the minced parsley, coating all sides evenly.
   Look for Each loin is fully covered with a thin, even layer of cheese and herbs.
   Tip Let the coated cod rest for 5 minutes so the crust adheres better.

The lemon wheels are thin and even, the garlic and parsley are minced, and the parmesan is freshly grated. The cod loins are dry and evenly coated with the cheese-herb mixture. The coating should feel like a thin, even layer that clings to the fish. Everything is ready to go.

Sear and Baste

3. 3Sear the cod in foaming lemon garlic butter
   Heat a large cast iron skillet over medium-high heat. Add the butter and let it melt until foaming. Add the minced garlic and cook for 30 seconds until fragrant. Place the cod loins in the skillet, crust-side down. Sear for 3–4 minutes until the crust is golden and crisp.
   Look for The butter foams and the garlic sizzles; the crust turns deep golden.
   Tip Don't move the fish while searing — let the crust set.
4. 4Flip and finish cooking the cod
   Carefully flip each loin with a fish spatula. Spoon the foaming lemon-garlic butter over the top of the fish continuously for 3–4 minutes, until the cod is opaque and flakes easily. The internal temperature should reach 145°F (63°C).
   Look for The fish turns opaque and the butter is golden and nutty.
   Safe temperature 145°F (63°C) internal temperature (fish)
   Tip Use a thermometer for accuracy — the fish should read 145°F (63°C).

The butter is foaming and the garlic is fragrant. The cod sears undisturbed until the crust is golden and crisp. As you flip and baste, the fish turns opaque and the butter becomes nutty. The kitchen smells rich and savory. The crust is golden, and the fish is just starting to flake.

Wilt and Finish

5. 5Wilt the spinach around the fish
   Add the baby spinach to the skillet around the cod. Toss it gently in the residual butter and pan juices. Cook for 1–2 minutes until the spinach is just wilted and bright green.
   Look for The spinach collapses and turns glossy, still vibrant.
   Tip Don't overcook — wilted but not mushy.
6. 6Finish with lemon wheels and extra parmesan
   Arrange the lemon wheels around the skillet or on a serving platter. Spoon the remaining foaming butter over the fish. Sprinkle with the reserved 1/4 cup of grated parmesan. Serve immediately with the wilted spinach and lemon wheels.
   Look for The fish glistens with butter and the parmesan melts into the crust.
   Tip Squeeze a lemon wheel over the fish just before eating for brightness.

The spinach is wilted and glossy, bright green, and seasoned with the pan butter. The lemon wheels are arranged around the skillet.

A final spoonful of foaming butter and a shower of parmesan create a glistening, golden finish. The fish is flaky and tender, and the dish is ready to serve.

Common mistakes

One common mistake is moving the fish too soon — let the crust set before flipping. Another is using pre-grated parmesan, which won't brown as well. Overcooking the fish is easy to avoid with a thermometer.

Also, don't crowd the pan; if the cod loins are too close, they will steam instead of sear. Finally, don't skip the basting — it's what keeps the fish moist and flavorful.

How to tell it’s done

The cod is done when it flakes easily with a fork and the internal temperature reaches 145°F (63°C). The crust should be deep golden and crisp, and the fish should be opaque all the way through.

The spinach is done when it is wilted and bright green, with no raw crunch left. The butter should be foamy and lightly browned, with a nutty aroma. Serve immediately while the crust is still crisp.

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