Harvest Potato Gratin
A flavor-filled holiday side that’s perfect for a crowd. A quick herby bechamel is made, then lots of salty nutty gruyere and pecorino is added, poured atop paper-thin sliced potatoes and baked until golden brown cheesy perfection. To make ahead, bake for the allotted 1 hour and 15 minutes, then leave to cool and refrigerate, covered. On the day of, remove from the fridge and bring completely to room temperature. Then sprinkle cheeses and bake uncovered for 30 minutes.
Note: For this recipe you can use all russet potatoes or use a mix of any combination of sweet potato, purple potatoes, or Japanese sweet potato for more variety and texture.
Serves 8-10
INGREDIENTS
4 tbsp unsalted butter, plus more for the pan
1 tsp smoked paprika
1 tsp mustard powder
¼ tsp nutmeg
5 garlic cloves, thinly sliced
1 tbsp thyme
½ tbsp rosemary, minced
4 scallions, thinly sliced, white and green parts separated
4 tbsp all-purpose flour
2 cups whole milk
1 cup chicken or vegetable stock
1 tbsp soy sauce
1½ tsp kosher salt
½ tsp freshly ground black pepper
1 cup freshly grated gruyere, divided
½ cup grated pecorino, divided
3½ to 4 lbs. russet potatoes (see note)
METHOD
Preheat oven to 350F and generously butter a 2 quart casserole dish.
In a saucepan over medium heat, melt butter, then add, add nutmeg, mustard powder, paprika, thyme, rosemary, scallion whites and garlic. Stir to combine.
Add flour, lower heat to medium low and then whisk for 30 seconds to 1 minutes to fully incorporate flour and a roux has formed. Whisk in milk and soy sauce and stir until thickened. Season with salt and pepper. Turn heat to low and stir in half the gruyere and half the pecorino until fully melted through and combined.
Peel potatoes and using a mandolin or a very sharp knife, cut into thin 1/8” slices.
Pour a third of the sauce into the casserole dish and spread into an even layer, then arrange potato slices in a vertical spiral, tucking in as many slices as possible. Pour remaining sauce atop and use a brush to spread across all the potato slices.
Cover with foil, place on a sheet pan and bake for 1 hour and 15 minutes. Uncover, sprinkle with remaining gruyere and pecorino along with half of the scallion greens. Bake, uncovered for another 25 to 30 minutes or until top is golden brown and bubbling and potatoes are tender. To serve, garnish with remaining scallion greens and serve hot.