Cheesy Potato Gratin Casserole Recipe
Warm, bubbling, and rich with creamy layers, a cheesy potato gratin casserole feels like comfort served straight from the oven. It’s the kind of dish that fills the kitchen with a cozy aroma and brings everyone to the table without calling twice. Thin slices of tender potatoes baked in a smooth cheese sauce create a golden, satisfying bite every time. Whether you’re planning a family dinner or a holiday spread, this recipe delivers dependable flavor, simple steps, and consistent results.
Equipment Needed
- Sharp chef’s knife or mandoline slicer
- Cutting board
- Medium saucepan
- Whisk
- Measuring cups and spoons
- 9×13-inch baking dish or casserole dish
- Aluminum foil
- Oven mitts
- Wooden spoon or silicone spatula
Ingredients List
Potato Layer
- 2½ pounds russet or Yukon Gold potatoes, peeled and thinly sliced (about ⅛-inch thick)
- 1 teaspoon salt
- ½ teaspoon black pepper
Cheese Sauce
- 3 tablespoons unsalted butter
- 3 tablespoons all-purpose flour
- 2½ cups whole milk, warmed
- 1 teaspoon garlic powder
- ½ teaspoon onion powder
- ½ teaspoon paprika
- 1½ cups shredded sharp cheddar cheese
- 1 cup shredded mozzarella cheese
- ½ cup grated Parmesan cheese
For Topping
- ½ cup extra shredded cheddar or mozzarella
- 1 tablespoon chopped fresh parsley (optional)
Step-by-Step Instructions
- Preheat the Oven
Preheat your oven to 375°F (190°C). Lightly grease the baking dish with butter or cooking spray to prevent sticking and ensure easy serving later. - Prepare the Potatoes
Peel and slice the potatoes into thin, even rounds. Uniform slices help them cook evenly and create neat layers. Place the slices in a bowl and season with salt and black pepper. Gently toss to coat. - Start the Roux
In a medium saucepan over medium heat, melt the butter completely. Add the flour and whisk continuously for about 1 minute. This removes the raw flour taste while forming a smooth base. - Add the Milk Slowly
Pour in the warm milk gradually while whisking. Keep stirring to avoid lumps. The mixture should begin to thicken after 3–4 minutes. - Season the Sauce
Stir in garlic powder, onion powder, and paprika. Reduce heat to low and let the sauce simmer gently until it becomes smooth and creamy. - Melt the Cheeses
Add cheddar, mozzarella, and Parmesan cheese to the sauce. Stir until fully melted and silky. Remove from heat once the sauce is uniform and thick. - Layer the Casserole
Arrange half of the sliced potatoes evenly in the baking dish. Pour half of the cheese sauce over the potatoes, spreading gently with a spoon. Add the remaining potatoes and cover with the remaining cheese sauce. - Add the Topping
Sprinkle the extra shredded cheese evenly over the top. This creates a golden crust during baking. - Bake Covered
Cover the dish loosely with aluminum foil and bake for 40 minutes. This allows the potatoes to soften without browning too quickly. - Bake Uncovered for Browning
Remove the foil and bake for an additional 20–25 minutes, or until the top is golden and the potatoes are fork-tender. - Rest Before Serving
Let the casserole rest for 10 minutes after removing from the oven. This helps the layers set and makes slicing easier.
Nutrition Facts (Approximate Per Serving)
| Nutrient | Amount |
|---|---|
| Calories | 420 kcal |
| Protein | 16 g |
| Carbohydrates | 32 g |
| Fat | 26 g |
| Saturated Fat | 15 g |
| Fiber | 3 g |
| Sugar | 5 g |
| Sodium | 620 mg |
| Calcium | 280 mg |
Values are estimates and may vary based on portion size and ingredients used.
Helpful Tips
Slice the potatoes as evenly as possible to ensure uniform cooking. A mandoline slicer makes this easier and faster. Warm milk blends better with the roux and helps prevent lumps in the sauce. If the cheese sauce thickens too much, stir in a splash of milk to loosen it. Always rest the casserole before slicing so the layers hold their shape and stay creamy inside.
Variations
For extra flavor, add ½ teaspoon dried thyme or rosemary to the cheese sauce. If you prefer a richer dish, replace ½ cup of milk with heavy cream. Thinly sliced onions or sautéed mushrooms can be layered between the potatoes for added depth. A mild spice kick can come from a pinch of cayenne pepper or chili flakes. For a lighter texture, use part-skim mozzarella while keeping sharp cheddar for flavor.
How to Serve
Cheesy potato gratin casserole pairs beautifully with roasted chicken, grilled steak, baked fish, or vegetable dishes. It works well as a main dish for simple meals when served with a fresh green salad. For gatherings, serve it hot directly from the casserole dish with a wide spatula to keep portions intact. A light garnish of fresh parsley adds color and freshness without overpowering the flavors.
Storage Instructions
Allow leftovers to cool completely before storing. Transfer the casserole to an airtight container or cover the baking dish tightly with plastic wrap or foil. Refrigerate for up to 3–4 days. To reheat, place portions in the oven at 350°F (175°C) until warmed through, or microwave individual servings in short intervals. For longer storage, freeze tightly wrapped portions for up to 2 months. Thaw overnight in the refrigerator before reheating.
FAQs
Can I make this casserole ahead of time?
Yes, assemble the casserole up to one day in advance, cover tightly, and refrigerate. Bake when ready, adding an extra 10–15 minutes to the covered baking time.
What potatoes work best for gratin?
Yukon Gold potatoes provide a creamy texture, while russet potatoes give a fluffy interior. Both work well in this recipe.
Why is my sauce grainy?
Graininess can occur if the sauce overheats or if pre-shredded cheese with additives is used. Use gentle heat and freshly grated cheese for smoother results.
Can I reduce the cheese?
You can slightly reduce the cheese, but the casserole may be less creamy. Balance flavor by keeping at least two types of cheese.
How do I know when the potatoes are fully cooked?
Insert a fork or knife into the center. It should slide in easily without resistance.
Conclusion
Cheesy potato gratin casserole delivers dependable comfort with every bite, blending tender potatoes and rich cheese sauce into a satisfying baked dish. With simple ingredients, clear steps, and flexible variations, it fits both everyday dinners and special gatherings. Prepared with care and served warm, this casserole brings warmth, flavor, and a sense of home to the table.
