I've made scalloped potatoes using both russets and Yukon Golds, and each has advantages. The russets pick up more of the flavour of the cream, while the Yukons were firmer and retained more of the flavour of the potato. In this case, I ruled in favour of richness. The russets got the nod.
Whichever you pick, all of the potatoes must be sliced to the same thickness or they'll cook unevenly. For a home book working with a knife, this task can be a bit of a challenge. Fortunately, there are a couple of tools to streamline the process: a food processor fitted with the slicing blade (in which case the potatoes will need to be trimmed to fit through the feed tube) and a mandoline (a hand-held slicer). Please, if you're working with a mandoline, use the guard and be careful when you slice the potatoes.
When I first learned how to make scalloped potatoes, the routine was to arrange the slices in several layers, seasoning each layer before adding the next, then pour the cream, cream sauce or milk on top. But somehow the final dish never seemed properly seasoned.
A better method is to add an exact amount of salt, garlic and thyme to the milk and cream mixture, then to pour it — deeply seasoned and hot — onto the potatoes. Believe me, those tubers drink it in like they'd been stranded in the desert for a week. And the finished product is amazing.
Start to finish: 1 hour 30 minutes (35 minutes active)
1 1/2 cups whole milk
1 1/2 cups heavy cream
1 teaspoon chopped fresh thyme
1 bay leaf
2 garlic cloves, smashed
1 1/2 teaspoons kosher salt
1/2 teaspoon ground black pepper
3 pounds russet potatoes
1 1/2 cups grated Parmesan cheese
Heat the oven to 375 F. Adjust an oven rack to the middle position.
In a medium saucepan, combine the milk, cream, thyme, bay leaf, garlic, salt and pepper. Bring the mixture to a boil, then remove from the heat, cover and let steep while you prepare the potatoes.
Peel the potatoes, then using a mandoline or the slicing disk of a food processor, slice them crosswise into 1/8-inch-thick rounds. Remove and discard the bay leaf and garlic cloves from the milk mixture, then pour about a quarter of the mixture into a 9-by-13-inch baking pan.
Add the potatoes, then the remaining milk mixture to the baking pan. Stir the potatoes to make sure they are separated, then press them down to distribute them evenly. Bake the potatoes on the middle shelf of the oven until the liquid has thickened and the top is golden, about 40 minutes. Sprinkle the Parmesan evenly over the tops of the potatoes, return the pan to the oven and bake until the top is browned, about 10 minutes.
Cool for 5 minutes before serving.
Nutrition information per serving: 390 calories; 200 calories from fat (51 per cent of total calories); 23 g fat (14 g saturated; 0.5 g trans fats); 80 mg cholesterol; 40 g carbohydrate; 3 g fiber; 5 g sugar; 10 g protein; 680 mg sodium.
EDITOR'S NOTE: Sara Moulton was executive chef at Gourmet magazine for nearly 25 years, and spent a decade hosting several Food Network shows. She currently stars in public television's "Sara's Weeknight Meals" and has written three cookbooks, including "Sara Moulton's Everyday Family Dinners."