Preheat oven to 425 degrees. Line a 9 by 12-inch baking dish with parchment paper.

Rinse cod fillets under cold running water and pat dry with paper towels. Place cod fillet(s) in prepared dish and brush with lemon olive oil. In a small bowl, combine feta cheese, lemon zest and dill (I use my hands); sprinkle on top of the cod.

Roast in the preheated oven, uncovered, 8 to 10 minutes per 1-inch of thickness (at its thickest point), until opaque and just cooked through. The cooking time is dependant on the thickness of the fillets; it is done when the internal temperature in the middle of the thickest part of the cod reaches 135 to 140 degrees on an instant read thermometer.

Switch the heat to broil and broil for 2 minutes to melt and lightly brown some of the cheese. Keep a close eye on it to make sure it doesn’t burn! Remove from oven and, because it will keep cooking, let the fish rest at room temperature for 5 minutes.

In a large sauté pan or skillet, heat 2 teaspoons regular extra virgin olive oil over medium heat. Add green onions, garlic and around half of the spinach. Cook, stirring, just until the spinach is wilted. Add remaining spinach and continue to cook, stirring, just until wilted.

Remove from heat and stir in bread crumbs and red pepper flakes (if using); season to taste with salt and pepper.

Divide cooked spinach among four dinner plates. Top with cod fillet. Serve immediately, with lemon wedges on the side.