Preheat the Oven: Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper or lightly grease it with cooking spray.
Prepare the Cod Fillets: Use paper towels to gently blot the cod fillets, absorbing any excess moisture. This will help the seasoning stick better and result in a flakier texture.
Make the Seasoning Mix: In a small bowl, combine the olive oil, melted butter, lemon juice, and minced garlic. Stir in the paprika, dried thyme, dried parsley, onion powder, salt, and pepper until well mixed.
Season the Cod: Arrange the cod fillets on the lined baking sheet. Brush the seasoning mix generously over each fillet, making sure to coat them evenly on all sides.
Bake the Cod: Bake the cod in the preheated oven for 12-15 minutes, or until the fish is opaque and flakes easily with a fork. The internal temperature needs to hit 145°F (63°C).
Serve and Garnish: Remove the cod from the oven and let it rest for a minute. Transfer to a serving plate and garnish with lemon slices and fresh parsley, if desired.