Wash and boil the potato until tender. Peel and cut into thin rounds.
Combine eggs and egg whites in medium bowl. Whip the eggs until well mixed. Add bouillon and fold over to combine all ingredients.
Heat oil in a small nonstick skillet. Add onions and potatoes to skillet. Cook until the potatoes are golden brown. Add spinach, cook for 1 minute until wilted.
Add egg mixture. Cook for two minutes. Transfer to a preheated oven for 8 to 10 minutes at 425°F. Cook until eggs are set and top is lightly browned.
Allow to cool. Slice into wedges. Sprinkle each wedge with Manchego cheese and serve.