Herbed Winter Root Vegetable Gratin with Rosemary and Sage

Winter cooking is about making the most of what keeps. By January, the root cellar and the farmers market are down to the sturdy stuff: potatoes, parsnips, rutabagas, carrots, and onions. These are not glamorous vegetables, but they are reliable, and when you bake them in cream with rosemary and sage, they become something worth waiting for.

A gratin is essentially a casserole with a fancy name, and it is one of the most forgiving things you can make. The technique is simple: slice the vegetables thin, layer them with herbs and seasoning, pour over cream, and bake until everything is tender and the top is browned. The herbs are what lift it out of the ordinary. Rosemary brings a resinous, almost piney note, while sage adds a soft, savory depth. Together they taste like a walk through a winter garden.

Choosing and Slicing the Vegetables

You can use any combination of roots you like, but a good starting mix is equal parts potato, parsnip, and rutabaga. Potato gives body and creaminess. Parsnip brings sweetness. Rutabaga, sometimes called swede, adds a peppery bite that keeps the dish from being too rich. If you have celeriac or turnip, they work well too. Avoid beets unless you want everything to turn pink.

Slice everything as thinly as you can, ideally with a mandoline. Uniform slices cook evenly, and uneven ones mean some pieces turn to mush while others stay crunchy. If you do not have a mandoline, use a sharp knife and take your time. Aim for slices about an eighth of an inch thick. No need to peel the potatoes if the skins are clean and thin; the parsnips and rutabaga should be peeled.

Layering and Baking

Rub a baking dish with butter and a cut clove of garlic. Start with a layer of potatoes, slightly overlapping, then a layer of parsnip and rutabaga. Season each layer with salt, pepper, and a scattering of chopped rosemary and sage. Repeat until you run out of vegetables, finishing with a layer of potatoes on top, arranged in a neat pattern if you are feeling fancy.

Pour over enough cream to come about three-quarters of the way up the vegetables. You can use half cream and half whole milk if you want it lighter, but do not use skim milk, which will split. Dot the top with small pieces of butter and cover the dish with foil. Bake at 375 degrees for about forty-five minutes, then remove the foil and bake another thirty to forty minutes, until the top is deeply golden and a knife slides through the vegetables with no resistance.

Let the gratin rest for fifteen minutes before serving. This is important, because it allows the cream to thicken and the layers to set. Cut it into squares and serve alongside roast chicken, pork, or a simple green salad. It reheats well, and some people insist it is even better the next day, when the flavors have had time to settle. Either way, it is a dish that makes a cold night feel generous.