Preheat oven to 350°F, spray an 8 × 8 inch baking dish with nonstick cooking spray, line with parchment paper. Spray parchment paper with cooking spray.
In a large mixing bowl, mix together all ingredients. Stir to combine.
Pour into prepared pan and bake for 50 to 55 minutes or until completely set in the middle. Let cool for 10 minutes before slicing.
Serve warm or at room temperature.
Notes
If you prefer, substitute 7 large eggs for the egg whites.
Store baked egg casserole in the refrigerator for up to 4 days or freeze for up to 3 months.