Traditionally a gratin is a layered dish topped with either grated cheese or a mixture of breadcrumbs and melted butter. I decided to forgo both in this case, but feel free to make this using either ½ cup grated Gruyere cheese or ½ cup of coarse breadcrumbs combined with 2 Tbsp. melted butter and scatter over top before baking. If you would like to change up the veggies you could use celeriac instead of the turnips and also you can substitute sautéed leeks for the onions and garlic. I find the combination of celeriac and potatoes to be absolutely yummy!
Makes 4 – 6 Servings
1 ½ lbs. Yukon Gold potatoes or other waxy type potatoes
½ lb. yellow turnip
1 cup whipping cream
½ cup homogenized milk
1 thinly sliced, peeled shallot
½ large clove garlic, minced
½ – 1 tsp. dried sage, or 1 ½ tsp. to 2 tsp. chopped fresh sage or substitute fresh or dried thyme
2 tsp. unbleached flour
1 tsp. salt
¼ tsp. or so freshly ground black pepper
Note: You can substitute a mixture of a sautéed medium onion, thinly sliced and a clove of garlic, sautéed in 1 Tbsp. butter for the shallot and raw minced garlic.
Preheat oven to 375 F.
Peel the potatoes (or not) and the turnip. Slice both thin 1/8” using a mandoline or a knife. Either butter or spray with non-stick cooking spray, an 8” square or round glass or a ceramic baking dish with 2” high sides. Begin layering the potatoes and turnip, sprinkling with salt and pepper, to taste, scattering with 1/3rd the shallot, half the garlic, 1/3rd of the sage and half the flour (you will be making a total of 3 layers); continuing layering in the same manner, the top layer consisting of potatoes, turnips, remaining shallot and a sprinkle of salt and pepper. If you are using the sautéed onions and garlic, scatter 1/3rd of the mixture between the layers, using the last 1/3rd for the top, instead of the shallot and raw garlic.
Place the cream and milk into a 4 cup measuring cup or microwavable bowl. Heat the milk on med-high in the microwave until tiny bubbles form around the edges of the cup or bowl, approximately 2 minutes. Once the cream mixture is “scalded” pour over the potato mixture; cover tightly with tin foil and bake for 45 minutes. Remove the foil, continue baking until lightly browned on top and veggies are tender. Remove from the oven and cool 5 minutes or so before serving.