Preheat oven to 350°F and spray a 9x13-inch baking dish with cooking spray.
Layer half of the waffle pieces in the bottom of the prepared dish, then top with diced chicken and 1 cup of shredded cheese.
In a large bowl, whisk together eggs, milk, maple syrup, salt, and pepper until well combined.
Pour egg mixture evenly over the waffle and chicken layers, then top with remaining waffle pieces and cheese.
Cover with foil and bake for 30 minutes, then remove foil and bake an additional 15 minutes until golden and set.
Let cool for 10 minutes before serving. Drizzle with extra maple syrup if desired. To freeze, cool completely, wrap tightly in plastic wrap and foil, and freeze for up to 3 months. Thaw overnight in refrigerator and reheat at 350°F for 25-30 minutes.