Preheat the oven to 400°F (200°C). Lightly grease a 9x13 baking dish.
Line the bottom of the baking dish with thin lemon slices to create a natural base for the fish.
Dry each cod fillet thoroughly with paper towels. Season both sides with salt, pepper, and paprika.
Whisk together melted butter, lemon juice, lemon zest, minced garlic, thyme, and dried parsley in a small bowl until combined.
Place the seasoned cod fillets on top of the lemon slices and pour the butter mixture evenly over each piece.
Bake for 15 to 18 minutes until the fish is opaque and flakes easily with a fork. Internal temperature should reach 145°F.
Optional: Switch to broil for 2 minutes to lightly brown the tops for added color and texture.
Garnish with fresh parsley and serve immediately directly from the baking dish.