Sprinkle the zucchini with the salt and toss to combine. Transfer to a colander and allow to drain for 30 minutes. Preheat oven to 400. Squeeze out any excess moisture and transfer the zucchini to a large mixing bowl. Add the bread crumbs and toss to combine.
In a separate mixing bowl, whisk together the egg, mayonnaise, Old Bay seasoning, mustard, and parsley. Pour the wet mixture over the zucchini and bread crumbs. Season with black pepper. Toss to combine until the wet mixture is completely incorporated into the zucchini and bread crumbs. Shape the mixture into 8 cakes and set aside.
Place cakes onto baking sheet. Bake on each side for 10 minutes.