Wash the kale; drain the artichokes. Chop the kale and the artichokes into bite-sized pieces, enough for 1 cup each. Grate the Pecorino Romano cheese.
In a medium bowl, whisk together the eggs, milk, and kosher salt until thoroughly combined. Stir in the cheese, artichokes and fresh ground pepper.
Place a dry cast iron skillet over medium heat. When hot, add kale and sprinkle with a bit of salt. Sauté with 1/4 cup water until tender, about 2 minutes. Remove the kale from the skillet and add it to the egg mixture.
Turn the heat to low. Add olive oil and rotate the pan to coat. Pour in the egg and vegetable mixture and spread the vegetables so that they are level. If necessary, shake the pan to even out the eggs. Cook the frittata over low heat for about 10 minutes, until the underside is set but the top is still slightly runny.
To finish the frittata, place the skillet under a pre-heated broiler until golden brown, about 2 to 3 minutes. Allow to cool for at least 5 minutes, then remove to a plate and cut into slices to serve. (Frittata can also be served at room temperature or cold.)