I use a classic rich combination of cream, butter, and garlic to draw out the seductive qualities of soft parsnips and kale. Together, they make a decadent, delicious dish.
Preheat the oven to 350 degrees F. Butter a medium baking dish with a tablespoon of the butter, then scatter half of the garlic on the bottom and set aside.
Heat the remaining tablespoon butter in a small saucepan over medium-low heat. Add the shallots and remaining garlic and stir until softened, about 3 minutes. Add the cream and nutmeg, and a generous amount of salt and pepper, and bring to a simmer.
Arrange half the parsnips in the gratin dish, working in a circle and overlapping the edges. Be sure to cover the bottom well because it will cook down to form one thick layer. Sprinkle with half the cheese, then spoon on half the cream. Layer the remaining parsnips, cheese, and cream mixture, then add the kale on the top layer, nestling it in between the slices of parsnip.
Put the dish on a baking sheet (to catch any drips) and bake until the parsnips are tender and the gratin is bubbling and beautifully browned on top, about an hour.