A healthy alternative to the cheesy omelet: a frittata studded with Swiss chard, which delivers iron, potassium, and fiber. Using mostly egg whites in place of the usual whole eggs lowers the calorie count.
Preheat oven to 375 degrees. Whisk together egg, whites, ricotta, 1/4 teaspoon salt, and the pepper in a medium bowl.
Heat oil in a 10-inch ovenproof skillet over medium-high heat. Add Swiss chard stalks and onion, and cook until onion is tender and translucent, about 4 minutes. Add Swiss chard leaves, and cook, stirring, until tender, about 1 1/2 minutes. Sprinkle with remaining 1/4 teaspoon salt. Add egg mixture, and stir once or twice to distribute vegetables evenly. Place skillet in oven, and bake until eggs have set, about 13 minutes. Serve immediately.