Recipe adapted from Curtis Stone.
5 ounces bacon, diced
1 cup white onion, chopped
2 garlic cloves, finely chopped
1 cup heavy whipping cream
1/2 cup whole milk
2 tablespoons fresh thyme, finely chopped
4 pounds Yukon Gold potatoes, peeled
1 1/2 teaspoons kosher salt
1 teaspoon freshly ground black pepper
2 cups Monterey Jack cheese, grated
1/2 cup Parmesan cheese, freshly grated
Saute bacon in a large pan until crisp, but not overcooked. Transfer bacon to a bowl, leaving two tablespoons of the bacon fat in the pan. Over a medium heat, add the onions and cook for several minutes. Add the garlic and stir for an additional minute. Add the cream, milk, and thyme and bring the mixture to a simmer. Turn off heat and reserve. Cut potatoes into 1/8" thick slices using a mandolin or a sharp knife. If you are using a knife, cut your first 1/8" thick slice, and then turn the potato on its flat side for remaining slices. This way the potato will not slip when using a sharp knife. Once potatoes are sliced, add to the cream mixture in a large mixing bowl. Add the salt and pepper and toss potatoes.
Preheat oven to 350° F.
In a 13"x9" pan, add one-fourth of the potatoes, making sure to cover the whole pan. Add one-fourth of the cheeses. Continue adding the potatoes and cheese, one-fourth at a time. Cover the pan with tin foil and bake for 40 minutes. Remove tin foil and cook for an additional 20 minutes, or until potatoes are fork tender. Let rest at least 10 minutes before serving.