Preheat the oven to 425° F and place an oven rack in the center of the oven.
Heat a 10-inch skillet (cast iron or non stick works best) over medium heat. Add the oil and twirl the pan to evenly coat, making sure to coat the sides of the skillet. Add the scallions, and cook for about 1 minute, or until they begin to wilt. Stir in the asparagus stalks, season with a light touch of salt, and let it cook for about 2 minutes, or until the asparagus just start to soften, stirring occasionally. Stir in the ham and the kale leaves.
Quickly whisk together the eggs, half and half, 2 teaspoons salt, pepper, and the Parmesan cheese, then pour the eggs into the skillet. Sprinkle with feta cheese, nestle in the reserved asparagus tips, then place in the oven to bake for about 18-20 minutes, or until the frittata is lofty and the center is no longer runny when you insert a knife. Remove from the oven, let it stand for a few minutes before slicing and serving.
Leftover frittata wedges are great for mornings on the go! Just reheat in the microwave and you have a wholesome breakfast to fuel your day.