Preheat oven to 350 degrees. In a large pot of boiling salted water, cook pasta according to package instructions. Drain; return to pot. In a large skillet, melt butter over medium-high. Add onion and garlic; cook until onion is beginning to soften, 4 minutes. Add kale, cover, and cook until almost tender, about 5 minutes. Transfer to pot with pasta.
Stir in chicken, ricotta, lemon zest, and 1/2 cup Parmesan; season with salt and pepper. Transfer mixture to a 9-by-13-inch baking dish; top with 1/4 cup Parmesan. Bake until top is golden, 30 minutes.
This recipe was my first time cooking kale -- and it was quite good. I cut it back to make only three servings, and noting that the previous reviewer thought it needed more flavor, I deglazed the pan with sherry and added a few shakes of Worchestire sauce when stirring in the ricotta cheese. Only used a small container of ricotta (15 oz) -- 48 oz seems like a lot, even if making the full recipe for 8 servings.
I was a bit disappointed by this recipe. It tastes like all of the parts that are in it, but hasn't melded together. Perhaps it's because we didn't use a rotissere chicken... maybe the saltness would have helped the dish. We just baked some chicken breasts and found the whole thing rather boring. Added sauted garlic and cherry tomatoes to the leftovers and that helped somewhat.