Place egg, flour and Panko breadcrumbs in separate bowls. Season each piece of fish with the salt and lemon pepper seasoning.
Dip fish pieces in flour to coat both sides. Dip in egg, shake off excess, then in Panko bread crumbs, patting gently for coating to adhere.
Place a 13x9” baking dish in the oven to get hot for at least 15 minutes. Add the 3 tablespoons of the melted butter to the heated baking dish and arrange the fish sticks on top with plenty of room on each side so they “fry” not "steam".
Bake 10 minutes, carefully turn fish sticks and add remaining butter to pan. Finish baking 5-10 minutes or until the coating is crispy, golden and the fish is cooked through. Remove from oven and let rest 5 minutes.