01 - Preheat the oven to 400°F. Lightly grease a baking dish large enough to hold the fillets in a single layer.
02 - Pat haddock fillets dry with paper towels. Arrange them in the baking dish, drizzle olive oil, and season both sides with salt and freshly ground black pepper.
03 - In a small bowl, combine melted butter, lemon juice, lemon zest, capers, parsley, and minced garlic. Stir until blended.
04 - Spoon the lemon-caper mixture evenly over each haddock fillet.
05 - Bake for 15 to 18 minutes, or until the fish is opaque and flakes easily with a fork.
06 - Garnish with fresh lemon slices and additional parsley if desired. Serve immediately.