This is an elegant side dish and a real crowd-pleaser. Don’t rinse the potato slices, the starch helps to bind and thicken the gratin. Use a mandolin and much care to cut the vegetables into thin, even slices.

Recipe by Catherine Pla

Serves 8

2 T unsalted butter, plus more for greasing the baking dish
2 c half and half (or whole milk and cream)
3 medium Yukon Gold potatoes
2 medium turnips
3 T fresh thyme leaves
Kosher salt and ground pepper
1⁄2 c grated Gruyere cheese
1⁄4 c grated Parmesan cheese

Preheat the oven to 375 degrees. Butter a 13x9x2” baking dish with softened butter.

Place half and half and thyme in a large saucepan and heat. Peel potatoes and turnips and place a mandoline across the top of the pan. Slice potatoes and turnips into 1/8 “ slices directly into the hot half and half mixture. Simmer until potatoes are partially cooked and mixture begins to thicken, 10-12 minutes. Taste and adjust seasoning with salt and pepper.

Combine cheeses in a small bowl. Using a slotted spoon, remove vegetable slices from the pan and place into the buttered baking dish. Pour in enough of the cream mixture to barely cover the slices. Cover with cheese mixture and dot with butter.

Bake until the casserole bubbles around the edges, and the top is golden brown, about 50-60 minutes. Remove from the oven and allow it to sit for 20 minutes before serving.

Potato and Turnip Gratin with Thyme