In our experience, most recipes for scalloped potatoes take hours of work yet still produce unevenly cooked potatoes in a heavy, curdled sauce. This version is faster than most and produces layer upon layer of thinly sliced, tender potatoes, creamy sauce, and nicely browned, cheesy crust.
Simmering the potatoes briefly in heavy cream thinned out with milk before moving the production into a baking dish cut the cooking time significantly while also eliminating the risk of raw potatoes in the finished dish.
A sprinkling of cheddar cheese and a mere 20 minutes in the oven were enough to produce an appealingly browned, cheesy crust. Russet potatoes, thinly sliced, gave us neat layers with the best texture and flavour. For the fastest and most consistent results, slice the potatoes in a food processor.
Start to finish: 1 hour
2 tablespoons unsalted butter
1 small onion, chopped fine
2 cloves garlic, minced
4 pounds russet potatoes, peeled and cut into 1/8-inch-thick slices
3 cups heavy cream
1 cup whole milk
4 sprigs fresh thyme
2 bay leaves
2 teaspoons salt
1/2 teaspoon pepper
4 ounces cheddar cheese, shredded (about 1 cup)
Heat oven to 350 F. Melt butter in large Dutch oven over medium-high heat. Add onion and saute until it turns soft and begins to brown, about 4 minutes. Add garlic and saute until fragrant, about 30 seconds. Add potatoes, cream, milk, thyme sprigs, bay leaves, salt, and pepper 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 centre of potato slice with some resistance), about 15 minutes.
Discard thyme sprigs and bay leaves. Transfer potato mixture to 3-quart baking dish and sprinkle with cheese. Bake until cream has thickened and is bubbling around sides and top is golden brown, about 20 minutes. Let cool for 5 minutes before serving.