Steps

1. Preheat oven to 400 degrees.
2. Beat eggs and cheese in a large bowl and set aside.
3. Heat oil in a large ovenproof skillet over medium. Add onions and potatoes. Cook for about five minutes, stirring occasionally, until the potatoes begin to brown and are just cooked through. Add garlic, saute briefly. Begin adding kale, a cup at a time. Stir, let the kale wilt, then add the next cup. Cook until all the kale is wilted and is a bright green.
4. Turn off heat, add salt and pepper to taste. Add eggs, turn heat back on to medium. As the eggs begin to set, use a spatula to lift up the mixture around the edges of the pan and allow the eggs to flow underneath. Cook until the eggs set on the edges but the middle is still runny. Place skillet in oven and bake until the frittata is slightly browned and puffy, about 15 minutes.
5. Remove from oven and let cool for five minutes. Carefully slide frittata onto a serving plate. If the frittata is sticking to the skillet just serve from the skillet. The skillet will be hot so use an oven mitt or potholder.