Chicken and Kale Casserole

3/4 pound large pasta shells

2 tablespoons unsalted butter

1 large yellow onion, diced medium

3 garlic cloves, minced

2 bunches kale (1 1/2 pounds), tough stems and ribs removed, leaves coarsely chopped

2 cups shredded or chopped cooked chicken (from 1/2 rotisserie chicken)

1 container (48 ounces) ricotta

3 tablespoons finely grated lemon zest (from 2 lemons)

3/4 cup Parmesan, grated (2 1/4 ounces)

1. Preheat the oven to 350 degrees
2. Bring a large pot of salted water to a boil, then add the pasta and cook until al dente. Reserve 1 cup of pasta cooking water before draining, then return the pasta to the pot.


3. Meanwhile, melt the butter in a large (12-inch) skillet over medium-high heat until the foam subsides, then add the onion and garlic. Cook, stirring, occasionally until the onion is soft, 5-7 minutes.


4. Add kale, cover, and cook until the kale is almost tender, about ten minutes more. Transfer mixture to the pot with the pasta.
   
   
5. Stir in ricotta, lemon zest, 1/2 cup of Parmesan, pasta water, and salt and pepper to taste. Stir well, then transfer to a 9 x 13” baking dish and top with the remaining Parmesan. Bake until golden, about 30 minutes. Allow to cool 10 minutes before serving.