Holiday scalloped potatoes, with real cream

From Tastefully Done

This one is from Cook's Illustrated and it's really rich and creamy...not really for weeknights, but perfect for Easter/Christmas. I think the food processor is a necessary tool for getting the potatoes the right size...

Serves 8 to 10. Published February 1, 2005.

For the fastest and most consistent results, slice the potatoes in a food processor.

Ingredients
2 tablespoons unsalted butter
1 small onion , minced
2 medium cloves garlic , minced (about 2 teaspoons)
3 cups heavy cream
1 cup whole milk
4 sprigs fresh thyme
2 bay leaves
2 teaspoons table salt
1/2 teaspoon ground black pepper
4 pounds russet potatoes , peeled and cut into 1/8-inch-thick slices
1 cup shredded cheddar cheese (about 4 ounces)

Instructions
1. Heat oven to 350 degrees. Meanwhile, melt butter in large Dutch oven over medium-high heat until foaming subsides, about 1 minute. Add onion and sauté until it turns soft and begins to brown, about 4 minutes. Add garlic and sauté until fragrant, about 30 seconds. Add cream, milk, thyme, bay leaves, salt, pepper, and potatoes and bring to simmer. Cover, adjusting heat as necessary to maintain light simmer, and cook until potatoes are almost tender (paring knife can be slipped into and out of center of potato slice with some resistance), about 15 minutes.

2. Remove and discard thyme sprigs and bay leaves. Transfer potato mixture to 3-quart gratin dish and sprinkle with cheese. Bake until cream has thickened and is bubbling around sides and top is golden brown, about 20 minutes. Cool for 5 minutes before serving.