Here's what I would do, the more I think about this recipe. Mix 2 egg whites, 1/4 cup of milk and 2 table spoons of melted unsalted butter or margarine. This will cut a lot of fat. Then mix the flakes, spices, and Parmesan. Dip the zucchini in the wet mixture and then in the potato flake mixture. Bake at 300 for 10 to 15 minutes until golden brown.
Butter and milk are basic ingredients in boxed mashed potatoes. When you mix them all together and bake, they get crispy and golden brown.
OR ~ you could use non-fat buttermilk instead of eggs and butter, mix the dry incredients, soak in the buttermilk, dip in the dry ingredients, spray with butter cooking spray, and bake.