Preheat your oven to 350°F (175°C).
Lightly grease an 8x11-inch baking dish with cooking spray.
In a large mixing bowl, combine the hash browns, eggs, turkey ham, shredded cheese, onion powder, salt, and pepper.
Stir until all ingredients are evenly distributed.
Pour the mixture into the prepared baking dish.
Gently shake the dish side to side to create an even layer.
Bake uncovered for approximately 40 minutes, or until the top is golden brown and the center is fully set.
Remove from the oven and allow the casserole to cool for 10–15 minutes.
Slice into bars and serve.
Store leftovers for easy breakfasts throughout the week.