Using the broiler for this fish dinner brings out new flavors.
Heat broiler, with rack set 4 inches from heat. Line a rimmed baking sheet with aluminum foil. Place cod on baking sheet; season both sides with salt and pepper. Broil until opaque throughout, 6 to 8 minutes.
Meanwhile, in a small bowl, stir together butter, capers, and parsley; season with salt and pepper. Top cod with a dollop of caper butter; serve with lemon wedges.