Preheat oven to 350 degrees F.
In large skillet, preferably cast iron, cook the sausage.
Once cooked, add the kale and toss to combine, cook 2 minutes until kale is slightly cooked.
Remove sausage and kale from skillet and set aside.
Melt butter in same skillet over medium-high heat.
Add onions and potatoes and cook 7-10 minutes, until onions become translucent and potatoes begin to soften.
Whisk together eggs, milk, salt, and pepper.
Add sausage and kale back to skillet with the potato mixture. If you are not using an oven-safe skillet, combine potato mixture with sausage and kale in a 9" baking dish.
Pour egg and milk mixture into skillet/baking dish.
Top with cheese.
Bake in preheated oven for 35 minutes, until eggs are set and cheese is slightly golden.
Serve and enjoy!