Preheat oven to 375°F and grease a 9x13-inch baking dish.

In a large skillet, cook Italian sausage over medium heat, breaking it apart until browned. Remove excess grease if needed.

Add onion and garlic to the skillet and cook until softened, about 3 minutes.

Stir in the kale and cook until wilted, then remove from heat.

In a saucepan, heat heavy cream and chicken broth over low heat. Stir in Italian seasoning, red pepper flakes, salt, and pepper. Add ½ cup mozzarella cheese and ¼ cup grated parmesan cheese. Stir until the cheese is melted and the sauce has thickened enough to coat a spoon.

Layer half of the sliced potatoes in the prepared baking dish. Top with half of the sausage mixture, then half of the cream sauce. Repeat layers.

Sprinkle the remaining mozzarella and Parmesan cheese over the top.

Cover with foil and bake for 35 to 40 minutes or until the potatoes are tender. Remove foil and bake for another 10 minutes until golden and bubbly.

Let rest for 5 minutes before serving.