A frittata is an open-faced omelet. It's easier to make than traditional omelets because all the ingredients are combined at once so you don't have to fuss with flipping it over. Leftover cooked potatoes or frozen hash brown potatoes will also work in thi
Cook the potato in boiling water 5 minutes or until tender; drain.
Combine egg whites and eggs in a large bowl, stirring with a whisk. Stir in potato, Canadian bacon, salt, pepper, and spinach.
Coat a 9-inch cast-iron skillet with cooking spray; place over medium-high heat. Add onion; sauté 4 minutes or until tender. Add potato mixture to pan; cook over medium heat 5 minutes or until almost set. Sprinkle with cheese. Bake at 400° for 6 minutes or until set. Let stand 3 minutes; cut into 4 wedges.