Kale Gratin

Heat the oven (with the oven rack in the middle) to 400°F.

Slice the onion into thin half moons. Pull the kale leaves from their stems; discard stems. Tear the leaves into bite-size pieces (you should get 10-12 packed cups). Place in a salad spinner, wash, and spin dry.

Place a large skillet or large pot with lid on the stove and turn the heat on to medium. Add the oil and heat until it shimmers, about 1 minute. Add the onion and cook, stirring occasionally with tongs, until softened, 6 to 7 minutes. Add the kale, sprinkle the salt, and stir to mix in with the onions. Cover and cook until the kale is tender, 5 to 6 minutes (stir it once or twice during the cooking and be sure to cover after each stir).

Meanwhile, measure the cream in a liquid measuring cup. Add the Parmesan, nutmeg, and pepper (about 6 turns on pepper mill). Stir to combine.

Once the kale is tender, remove the lid and add the cream mixture. Stir while it comes to a boil (this should only take a minute). Pour the kale mixture into a shallow 1 1/2-quart baking dish. Sprinkle the remaining 2 tablespoons of Parmesan over the kale and bake until it bubbles, about 15 minutes.