- 4 Idaho potatoes, medium
- 1 tbsp garlic, chopped
- 1 leek, white and light green part only, cleaned and thinly sliced
- 1/2 cup Parmesan cheese, finely grated
- 3 tbsp butter
- 3/4 cup cream
- 1/4 tsp ground nutmeg
- Salt and freshly ground pepper
Preheat oven to 280 degrees. In a medium pot, melt 2 tablespoons of butter, add the leeks, cover, and cook on low heat until completely softened.
Brush a 12-by-8-inch glass or ceramic gratin dish with remaining melted butter. Spread the chopped garlic on the bottom of the dish. Peel the potatoes and cut them in very thin slices; use slicer or mandoline. Do not put potatoes in water after peeling, because this will remove the starch, which is needed to help thicken the cream during baking.
Layer the potato slices and the cooked leeks with the Parmesan cheese – reserving 1 tablespoon of cheese for the top. In small bowl, mix cream with salt, pepper, and the nutmeg. Pour the mixture over the potato and leeks, and sprinkle remaining cheese on top.
Bake uncovered until the potatoes are soft and golden brown on top. If gratin starts becoming too dark but the potatoes are not yet cooked, turn heat down to 250 degrees and finish baking.