Preheat the oven to 350 degrees F. and spray an 8x8 baking dish with nonstick cooking spray.
Evenly spread the spinach, bell peppers, onion, and ham across the bottom of the dish.
In a medium bowl, whisk together the eggs, egg whites, milk, garlic powder, onion powder, salt, and pepper until well combined.
Pour the egg mixture evenly over the vegetables and ham.
Sprinkle the reduced-fat cheddar evenly over the top.
Bake for 35-40 minutes, or until the center is set and a knife inserted in the middle comes out clean.
Let cool 5-10 minutes before slicing into 6 pieces.