Preheat oven to 200 degrees and have 4 oven proof plates ready.
Place the potatoes in a pot of water and bring to a boil over medium-high heat. Boil 20 minutes or until the potatoes are tender and easily pierced by the tip of a sharp knife. Drain the potatoes, peel them, and cut them into small cubes.
In a mixing bowl, combine the first five ingredients. Using a nonstick pan sprayed lightly with cooking spray and saute the mixture 3-5 minutes over medium heat (until mushrooms are soft).
In another bowl lightly beat the whole eggs with a fork then add in the egg whites until thoroughly blended. Add pepper to taste.
Spray an 8-inch nonstick pan and set over medium heat. Pour in 1/4 of the egg mixture. Cook 2-3 minutes. Lift up the sides of the omelet to allow the uncooked egg to flow to the bottom of the pan. When the egg is solidified, scatter 1/4 of the cooked artichoke/potatoe mixture into a line down the center of the omelet (you will be folding it over). Sprinkle with 1 Tablespoon of cheese. Using a spatula, carefully fold the omelet in half. Place on oven-proof plate and keep warm in the oven while you repeat the process for the remaining omelets. Serve and enjoy.