How to Make Scalloped Potatoes Step by Step

Understanding Scalloped Potatoes and What Makes Them Special

Scalloped potatoes are a classic comfort food dish that has been part of American cooking for generations. The dish consists of thinly sliced potatoes layered with a creamy sauce, typically made from butter, flour, milk, and cheese, then baked until the potatoes are tender and the top is golden brown. The name "scalloped" refers to the decorative, shell-like pattern that can be created when slicing the potatoes, though this is optional. What distinguishes scalloped potatoes from similar dishes like au gratin potatoes is that scalloped potatoes traditionally use a plain cream sauce, while au gratin specifically includes a cheese topping.

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The origins of scalloped potatoes trace back to European cooking traditions, particularly from France and Germany, where potato gratins became popular in the 18th century. When potatoes became widely available in America, cooks adapted these techniques to create the scalloped potato dishes we recognize today. The dish gained popularity throughout the 19th and 20th centuries and remains a staple at family dinners, holiday meals, and potluck gatherings across the country.

Understanding the basic structure of scalloped potatoes helps you execute the dish correctly. The potatoes provide the main substance and absorb the flavoring from the cream sauce. The sauce serves multiple purposes: it keeps the potatoes moist during cooking, adds richness and flavor, and helps cook the potatoes evenly. When baked, the starch from the potatoes helps thicken the sauce naturally, creating a cohesive dish rather than a watery one. A typical recipe serves four to six people and takes approximately one hour from preparation to serving.

Practical takeaway: Scalloped potatoes work well for family meals because they can be prepared in advance and reheated, making them convenient for busy schedules. The basic formula of potatoes plus cream sauce plus time in the oven is flexible enough to accommodate various ingredient preferences and dietary adjustments.

Selecting and Preparing Your Potatoes

Choosing the right potatoes significantly impacts the final result of your scalloped potatoes. Waxy potatoes, such as Red Bliss, Yukon Gold, or fingerling varieties, are ideal for this dish. These potatoes contain less starch than russet potatoes and hold their shape during cooking rather than breaking down or becoming mealy. A five-pound bag of potatoes typically costs between three and five dollars at most grocery stores and contains enough potatoes for a standard recipe serving four to six people. One pound of potatoes yields approximately three medium potatoes or about two and one-half cups when sliced.

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Before using your potatoes, wash them thoroughly under cold running water to remove any dirt or debris. You can scrub them gently with a vegetable brush if available, though this is optional. Pat them dry with a clean kitchen towel or paper towels. Do not peel the potatoes at this stage—peeling is easier and safer after washing but before slicing. For this recipe, you will need approximately two pounds of potatoes, which works out to six medium potatoes or about five to six cups of sliced potatoes.

When slicing potatoes for scalloping, consistency in thickness matters for even cooking. Aim for slices between one-eighth and one-quarter inch thick. A sharp chef's knife works well, or you can use a mandoline slicer if you have one available. A mandoline slicer can reduce slicing time from ten minutes to two or three minutes, but requires careful handling to avoid cutting your fingers. If you choose to use a mandoline, always use the hand guard provided and keep your fingers away from the blade. Place each slice immediately into a bowl of cold water as you slice to prevent browning and to rinse away excess starch, which helps the potatoes cook more evenly.

Practical takeaway: The choice between waxy and starchy potatoes makes a real difference—waxy potatoes maintain their shape and create a more attractive finished dish, while russet potatoes may become too soft and create a mushier texture. Soaking sliced potatoes in cold water for at least thirty minutes before cooking removes surface starch and contributes to better texture in the final dish.

Making the Cream Sauce Base

The cream sauce is the foundation of flavorful scalloped potatoes and requires basic cooking technique. Start by melting three tablespoons of unsalted butter in a medium saucepan over medium heat. Butter typically costs between three and five dollars per pound at grocery stores, and this recipe uses less than one-tenth of a standard pound. Once the butter is completely melted and foaming slightly, add three tablespoons of all-purpose flour and stir constantly for about one minute. This combination of butter and flour is called a roux, and it serves as the thickening agent for your sauce.

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After cooking the roux for one minute, gradually add three cups of whole milk while stirring continuously. Add the milk slowly—about one-half cup at a time—whisking thoroughly between additions to prevent lumps from forming. The mixture will initially look thin and watery, which is normal. Continue cooking and stirring over medium heat for approximately five to eight minutes until the sauce thickens enough to coat the back of a spoon. When you run your finger across the back of a coated spoon, the line should stay clear without the sauce running back together immediately.

Once your sauce reaches the proper thickness, season it with salt and freshly ground black pepper to taste. Start with one-half teaspoon of salt and one-quarter teaspoon of black pepper, then taste and adjust as needed. If you wish, you can add one-half teaspoon of dry mustard powder or one-quarter teaspoon of ground nutmeg for additional flavor complexity. Some cooks prefer to add one-half cup of shredded cheddar or gruyere cheese to the sauce for extra richness, though this is optional. Remove the sauce from heat and let it cool slightly before assembling your dish. At this point, the sauce can be made up to four hours in advance and stored in a covered container in the refrigerator.

Practical takeaway: Mastering the roux technique—melting fat, cooking flour in the fat, then gradually adding liquid—is foundational to many classic sauces. The key is stirring constantly and adding liquid slowly to prevent lumps. If lumps do form despite careful technique, strain the sauce through a fine-mesh strainer before using it.

Assembling and Seasoning Your Dish

Assembly happens in a baking dish, typically a nine-by-thirteen-inch rectangular dish or a similar-sized round dish. Grease the baking dish lightly with butter or cooking spray to prevent sticking. Drain your prepared potatoes thoroughly and pat them dry with paper towels to remove excess water. Wet potatoes can create a watery dish rather than a creamy one. Layer approximately one-third of the potatoes in the bottom of the prepared baking dish, spreading them into an even layer.

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Pour approximately one-third of your cream sauce over the potato layer, using a spatula or the back of a spoon to distribute it evenly. At this stage, you can sprinkle salt and pepper over the layer if desired. Repeat this process two more times: potatoes, sauce, seasoning. Your top layer should be sauce rather than potatoes, as this helps create a cohesive dish and allows the top to brown nicely. If you are adding cheese, sprinkle approximately one-half cup of shredded cheese over the very top layer. Gruyere, sharp cheddar, or Swiss cheese all work well, each providing slightly different flavor profiles.

At this point, the assembled dish can be covered with plastic wrap and refrigerated for up to twenty-four hours before baking. This advance preparation makes scalloped potatoes particularly practical for entertaining or holiday meals. The cold dish will require an additional ten to fifteen minutes of baking time compared to a room-temperature dish. Alternatively, you can bake the dish immediately after assembly. Cover the baking dish with aluminum foil to prevent the top from browning too quickly while the potatoes cook through.

Practical takeaway: Even layering of potatoes and sauce ensures every bite of the finished dish contains both potatoes and creamy sauce. The top layer of sauce helps bind all components together and creates a unified texture. Refrigerating the assembled dish actually improves flavor development, as the ingredients have time to meld together before cooking.