Mixed Potato Gratin

By charlotteh371

Ingredients

• 3 large Russet potatoes
• 3 large red-skinned sweet potatoes
• 1 1/2 cups heavy cream
• 2 garlic cloves, minced
• 1 tablespoon minced fresh thyme
• 1 1/2 teaspoons fine sea salt
• 1/2 teaspoon freshly ground black pepper
• 1 1/2 cups shredded Gruyère cheese
• 3/4 cup shredded parmesan cheese
• 2 tablespoons butter, cut into small pieces

Preparation

Step 1

Peel all of the potatoes.
2.Using a mandolin, food processor or very sharp knife, cut them into 1/8-inch-thick rounds and place them in a bowl.
3.In another medium sized bowl. combine the cream, garlic and thyme and set aside.
4.Place 1/2 cup of the shredded gruyere cheese aside to use for the topping.
5.Spray a 9x9 baking pan with cooking spray and layer the potatoes, alternating colors in 1 even layer. Sprinkle the top of this layer with some salt and pepper, a little bit of gruyere cheese and a little bit of parmesan cheese. Repeat this process until you use up all the potatoes. I had about 4 layers.
6.Preheat oven to 400°F.
7.Pour the heavy cream over the mixture once all your layers are done. Sprinkle the top with the remaining gruyere cheese and dot it with butter.
8.Cover gratin tightly with foil and bake for 30 minutes. Remove the foil and bake for 25 minutes longer. Let it set for a few minutes before serving.