Preheat oven to 425 degrees.
In a large bowl, whisk all ingredient (except the butter) in together, folding the kale and cheese last.
Add the butter to a cast iron skillet or pie pan (8 to 9 inches, if you go bigger than this, the edges will not rise as much and look more like a frittata) and place the skillet onto a baking sheet and then into oven to melt the butter, 1 to 2 minutes.
Once melted, pour the egg mixture into skillet and bake on the center rack for 25 to 30 minutes or until golden.
Serve and enjoy!