1-¼ cup shredded sharp cheddar cheese
1-¼ cup shredded Monterey Jack cheese
½ cup grated Parmesan cheese
2 teaspoons cornstarch
3 pounds Russet or Idaho potatoes—peeled and sliced 1/8 inch thick—use food processor or mandoline slicer—cannot hand cut to thinness needed!
¾ cup heavy cream
½ cup chicken broth
Combines cheeses—Adjust oven rack to middle position and heat oven to 350 degrees. Toss cheese and the cornstarch in large bowl until evenly coated.
Assemble gratin—Shingle half of the potatoes in large gratin dish, sprinkle evenly with ¾ teaspoon salt, ¼ teaspoon pepper, and half of the cheese mixture. Repeat potato layer, salt, and pepper layer. Combine cream and broth in large measuring cup and pour over potatoes. Top with the other half of cheese mixture.
Bake—bake until golden brown and fork inserted into center meets little resistance, about 75 to 90 minutes. Let cool 10 minutes to setup and then serve. Enjoy!