- 1 small rutabaga (12 ounces), peeled and cut into large dice
- 3 medium potatoes (1 1/4 pounds), peeled and quartered
- 2 medium-large turnips (12 ounces), peeled and quartered
- 3/4 cup freshly grated Parmesan cheese
- 2 tablespoons olive oil
- 3/4 teaspoons salt
- 1 teaspoon chopped fresh thyme leaves
- 1/4 teaspoon ground nutmeg
- 1/4 teaspoon cayenne pepper
- Bring a large pot of salted water to a boil. Add the rutabaga and cook for 20 minutes.
- Add the potatoes an turnips and cook for another 20 to 25 minutes, until all the vegetables are easily pierced with the tip of a paring knife.
- While the vegetables are cooking, preheat the oven to 400F and grease a 2-quart casserole dish with butter or cooking spray.
- Drain the vegetables, and while they are still hot, carefully press them through a ricer into a large bowl (the gratin is “fluffy” when riced).
- Add 1/2 cup of the Parmesan (leaving enough to dust the top) and all the remaining ingredients; stir to incorporate.
- Transfer the mixture to the casserole. Sprinkle the top with the remaining 1/4 cup Parmesan, and bake until heated through and the top is browned, about 20 minutes.