This scalloped potatoes recipe has been one of my most requested side dishes at family gatherings for years. I first learned to make it on a rainy Sunday when I wanted something comforting and a little bit indulgent but still simple enough to prepare while I watched the kids play. The thin, uniform slices of potato melt into a rich, velvety sauce made from butter, onion, milk, and chicken broth, then get a blanket of sharp cheddar and a shower of fresh thyme. Every summer barbecue and winter dinner since has felt incomplete without it. What makes this version special is the balance: not too heavy, with a gently seasoned white sauce that clings to each paper-thin slice, so every forkful delivers creaminess, tender potato, and a little hit of cheddar. I use a mandolin for consistency, but I’ll also share alternative slicing tips for anyone without one. It’s the kind of dish that reheats beautifully the next day and tastes even more cohesive after a short rest — a reliable crowd-pleaser that pairs with roasted meats, simple salads, or a holiday ham.

Ingredients

• Potatoes (8 cups / about 3 pounds): Choose starchy varieties like Russet or Yukon Gold for a tender bite that still holds shape; peel and slice thinly for even cooking. If you prefer waxy potatoes, expect a firmer texture.
• Butter (4 tablespoons): Use unsalted butter so you can control the seasoning. Real butter gives the base sauce a rich mouthfeel; substitute with salted and reduce added salt slightly if needed.
• Onion (1/2 cup, diced): Yellow or sweet onion works best — it softens and lends a gentle sweetness to the sauce. Finely dice so it cooks quickly and melts into the roux.
• Garlic (1 teaspoon, minced): Adds aromatic depth. Fresh is ideal; if using jarred, use about 1/2 teaspoon and taste as you go.
• Flour (6 tablespoons): All-purpose flour thickens the sauce. Cook it with butter to remove raw flour taste before adding liquids for a smooth, lump-free texture.
• Chicken broth (1 cup): Use low-sodium to control salt levels. Vegetable broth is a good swap to make the dish meatless, though it will shift the flavor profile slightly.
• Milk (2 cups): Whole milk gives the creamiest result; 2% works as a lighter option but expect a slightly thinner sauce.
• Dried thyme (1/2 teaspoon) plus fresh thyme (1/2 tablespoon + garnish): Dried thyme is cooked into the sauce for earthiness; fresh thyme added before baking gives a brighter herbal note and a fresh finish.
• Salt and pepper: Add to taste; start light and adjust after the sauce reduces and the cheese melts.
• Cheddar cheese (1 cup, grated): Sharp or extra-sharp cheddar melts into the sauce for tang and depth. Grate your own for the best texture and flavor.

Instructions

Prepare the baking dish and oven: Preheat the oven to 350 F. Spray a 9x13-inch baking pan with nonstick spray. Preheating ensures steady oven temperature so the potatoes cook evenly for the full bake time. Slice the potatoes: Wash, peel, and slice the potatoes very thin (about 1/8 inch). A mandolin gives consistent slices that layer and cook uniformly; if using a knife, aim for a uniform thickness and work patiently to avoid uneven cooking. Sauté aromatics and make the roux: In a large saucepan over medium-low heat melt 4 tablespoons of butter. Add 1/2 cup diced onion and 1 teaspoon minced garlic; sauté until translucent and soft, about 4 to 5 minutes. Stir in 6 tablespoons flour and cook for 2 more minutes to create a light roux that will thicken the sauce without tasting raw. Finish the sauce: Reduce heat to low and slowly whisk in 1 cup chicken broth, then add 2 cups milk, whisking constantly. Increase to medium and cook, stirring, until boiling and thickened — about 4 to 6 minutes. Season with salt and pepper to taste, then remove from heat and stir in 1/2 teaspoon dried thyme and 1 cup grated cheddar until smooth. Assemble the layers: Place half of the sliced potatoes in a single layer in the prepared pan. Season lightly with salt and pepper. Pour half of the cheese sauce over the potatoes, spreading gently. Add the second layer of potatoes, season, and pour the remaining sauce on top. Sprinkle 1/2 tablespoon fresh thyme over the surface. Bake and rest: Cover the pan tightly with foil and bake at 350 F for 45 minutes. Remove foil and bake uncovered another 30 minutes until the top is golden and sauce is bubbling. Let rest 10 to 15 minutes before serving so the sauce sets and slices hold together.

Storage Tips

After baking, allow the dish to cool to room temperature for no more than two hours, then cover tightly and refrigerate for up to 4 days. For freezing, bake only until the sauce thickens slightly (about 30 minutes), cool completely, cover with a double layer of foil and frozen within 2 hours. Reheat from thawed in a 350 F oven until heated through, about 30 to 40 minutes. Use airtight glass or metal pans for best results; avoid plastic lids in the oven.

Ingredient Substitutions

To make this meatless, swap the chicken broth for vegetable broth and proceed as written. For a gluten-free version, replace the all-purpose flour with a 1:1 gluten-free flour or use cornstarch (mix 2 tablespoons cornstarch with 3 tablespoons cold milk before adding to the sauce). Use half-and-half or cream for an ultra-rich version, but reduce baking time slightly to prevent separation. Cheese variations like Gruyere or fontina add depth.

Serving Suggestions

Serve alongside roasted turkey, glazed ham, or a simply grilled steak. Add a peppery arugula salad with lemon vinaigrette to cut richness, or roasted autumn vegetables for color. Garnish with additional fresh thyme sprigs and a light dusting of extra grated cheddar or cracked black pepper. For a brunch twist, top individual portions with a fried egg and chopped chives.

Cultural Background

Scalloped potatoes have roots in European peasant cooking where simple, starchy vegetables were layered with dairy to create filling dishes. Over time the recipe migrated to North America and evolved into numerous regional variations, some using cream and cheese, others relying on simple milk-based sauces. The word "scalloped" originally referred to a shallow dish; today it evokes layered, baked potato casseroles that comfort across many tables and seasons.

Seasonal Adaptations

In winter, add roasted garlic and a pinch of nutmeg to warm the flavor profile, and consider mixing in thinly sliced parsnips for complexity. In summer, lighten the dish with part-skim milk and brighter herbs like tarragon or chives. For holiday menus, top with panko and melted butter for a crunchy crust or fold in thinly sliced leeks for an onion-forward aroma.

Meal Prep Tips

Assemble the casserole the night before and keep covered in the refrigerator. Bring to room temperature for 30 minutes before baking and add 10 to 15 minutes to the bake time if still cold. Portion into individual ramekins for grab-and-go reheating, or freeze single servings for quick lunches. Label containers with the bake date and reheating instructions for easy family use.

Whether you’re serving this for weeknight comfort or a festive spread, these scalloped potatoes reward patience with reliable, creamy results. Make it your own by experimenting with cheeses and herbs, and enjoy the way it brings people together around the table.