Kale, Radish, And Leek Gratin With Gruyere Cheese

3 tbsp unsalted butter

3 leeks, white and light green parts, thinly sliced

2 bunches radishes, halved or quartered

1 bunch young kale, sliced

2 tbsp fresh chopped thyme, or 1 tsp dried thyme

1/2 tsp cayenne powder

kosher salt and black pepper, to taste

3/4 cup heavy cream

1/2 cup panko bread crumbs

1 1/2 cups grated gruyere cheese

Heat oven to 375F. In a 12 inch cast iron skillet, melt the butter over medium heat. Add the leeks and sauté, stirring frequently, until they are tender, about 6-8 minutes. Add the radishes and cook for 5 minutes. Add the kale and cook and until wilted, about 5 minutes. When the kale is wilted, stir in the thyme, cayenne, and cream. Bring to a simmer and cook for 2 minutes. Mix in the bread crumbs then top the gratin with the gruyere cheese. Transfer the skillet to the oven bake for 25-30 minutes. The gratin will be bubbling and the cheese will be melted and browned. Take the gratin out of the oven and let it sit and rest for 5 minutes before serving.