Unsalted butter
½ large celery root
6 tbsp extra virgin olive oil
1 lb red potatoes
2 large Bartlett pears
sea salt and freshly ground black pepper
¾ cup heavy cream
1 large clove of garlic, mashed
1 cup Gruyére cheese, grated
2/3 cup freshly grated parmesan cheese
1 tsp chopped fresh thyme
Preheat the oven to 375°.
Lightly butter a shallow baking dish with the unsalted butter and set aside.
Peel the celery root ad slice into ¼” thick slices. Heat the 2 tbsp of oil in a large skillet over medium heat and add the celery root. Cook, turning the pieces of celery root until they are lightly browned. About 10 minutes. Drain on a paper towel.
Peel the potatoes and also slice into ¼” thick slices. Add another 2 tbsp of oil to the pan and repeat as for the celery root.
Peel the pears and slice into ¼” thick slices. Add the remaining 2 tbsp of oil to the pan and again repeat as for the celery root and the potatoes.
Lightly season the celery root, potatoes, and pears with salt and pepper.
Heat the cream and garlic in a small saucepan over medium high heat, until just simmering. Remove from the heat.
In a small bowl, combine the Gruyére, parmesan, thyme and 1 tsp each of salt and pepper.
Layer the celery root in the prepared baking dish and sprinkle with 1/3 of the cheese mixture. Remove the garlic from the cream and drizzle ¼ of the cream over the cheese.
Layer the potatoes on top and top with another 1/3 of the cheese mixture. Drizzle with another ¼ of the cream.
Layer the pears n top and sprinkle with the remaining cheese. Drizzle with the remaining cream.
Cover the dish with foil and bake for 30 minutes. Then uncover and bake until the gratin is bubbly and browned.(5-10 more) Let cool 10-15 minutes before serving.