Potatoes Au Gratin Recipe

In a house with 8 kids, a side dish that disappears completely is the highest compliment I can get. This is one of those recipes. I set it on the table and by the time everyone has gone through the line, I am lucky if there is enough left for me. My boys especially — they go back for the crispy cheesy edges every single time. It is comfort food at its best and it costs almost nothing to make.

Try these other Au Gratin Recipes – Cauliflower au Gratin, Sweet Potato Au Gratin and Au Gratin Potatoes Crock Pot Recipe.

Why We Love This Recipe

• Costs just $6–8 to feed the whole family — a steakhouse-worthy side dish at a fraction of the price
• Made with pantry staples you already have — butter, flour, milk, russet potatoes, and shredded cheddar
• Rich, creamy, and cheesy with a golden bubbly top that looks impressive with almost no effort
• Perfect for holidays AND weeknights — make it ahead and just pop it in the oven when you need it
• Completely customizable — swap the cheese, add ham or bacon, or throw in fresh herbs
• Leftovers are somehow even better the next day — the sauce soaks into the potatoes overnight

Ingredients

Everything in this recipe is a basic pantry and grocery staple — nothing specialty, nothing hard to find. Here is what you need and why each ingredient matters.

• Russet potatoes — peeled and sliced into ⅛-inch thick slices. Russet potatoes are the best choice because they are high in starch and low in moisture, which gives you a creamy sauce that does not turn watery.
• White onion — adds a mild sweetness to every layer. Yellow onion works just as well.
• Butter — we use unsalted butter so we can control the salt level in the sauce.
• All-purpose flour — mixed with the butter to create a roux, which is what thickens the sauce and keeps it from curdling.
• Milk — whole milk gives the creamiest result. If your sauce comes out too thin, swap for heavy cream.
• Garlic powder — adds warmth and depth to the sauce without any chopping.
• Salt and pepper — season to taste.
• Sharp cheddar cheese — freshly shredded from a block. Sharp cheddar is bold enough to stand up to the potatoes and melts beautifully. See the cheese section below for alternatives.
• Fresh parsley — optional, for garnish.

Scroll to the bottom for the full recipe and ingredients in the recipe card.

How to Make Au Gratin Potatoes

Step 1 – Prepare oven and baking dish – Preheat the oven to medium heat 400 degrees F. Spray a 2.5 or 3 quart casserole pan with a non-stick cooking spray.  

Step 2 – Place Potatoes and Onions in dish – Layer the potatoes and sliced onions into the casserole dish.  You want to make slanted rows and layer the sliced potatoes on top of each, leaving room in between so the sauce can get into between the potatoes.  

Step 3 – Melt Butter and add other ingredients – Melt the butter in a medium saucepan over medium high heat.  Add the flour and stir until combined.  Then whisk in the milk, garlic powder, salt and pepper.  Cook for 2-3 minutes whisking continuously until the mixture thickens. 

Step 4 – Stir in cheese – Then remove the saucepan from the heat and then immediately stir in the ½ cup shredded cheeses.  

Step 5 – Pour over potatoes – Pour the cheese sauce even over the potatoes in the casserole dish making sure that they are all covered with the cheese sauce. 

Step 6 – Cover potatoes and Bake – Cover the casserole dish with foil and bake for 60 minutes.  Then remove the foil and bake for 20-30 minutes until the top of the potatoes are browned and the potatoes are fork tender. 

Step 7 – Serve and Enjoy – Let the potatoes sit for 20-30 minutes before serving.  Then top with the fresh parsley and it’s ready to enjoy.

Recipe Tips

• Always shred cheese from a block. Pre-shredded cheese has added starches that prevent smooth melting. Two extra minutes of grating makes a noticeably creamier sauce.
• Slice potatoes as evenly as possible. Aim for ⅛-inch slices — a mandoline slicer makes this fast and consistent. Uneven slices mean some potatoes will be undercooked while others are overdone.
• Layer with space between slices. You want the cheese sauce to get between every layer — do not pack them too tightly or the center will stay undercooked.
• Stir the sauce constantly. Once you add the milk to the roux, whisk continuously for 2–3 minutes until it thickens. Stopping too soon leads to a lumpy sauce.
• Remove from heat before adding cheese. Always take the saucepan off the heat before stirring in the shredded cheese. Adding cheese to a pan that is still on the heat causes it to seize and turn grainy.
• Let it rest before serving. This is the step everyone skips and then wonders why the sauce is runny. Let the dish sit for 20 minutes after it comes out of the oven — the sauce thickens as it cools slightly and the slices hold together when you serve them.
• Microwave shortcut for busy nights. Microwave the sliced potatoes and onions for 10 minutes before layering in the dish — this cuts the oven time significantly on weeknights.

Best Cheese for Potatoes Au Gratin

Sharp cheddar is our everyday go-to and it is available at every grocery store. It has enough bold flavor to come through in the creamy sauce and melts evenly when you shred it fresh from the block.

If you want to upgrade for a special occasion, Gruyere is incredible — rich, nutty, and melts like a dream. A mix of half sharp cheddar and half Gruyere is our favorite combination for holidays.

One rule that makes a real difference: always shred your cheese from a block rather than buying pre-shredded. Pre-shredded cheese is coated in starches that prevent it from melting smoothly. It takes two extra minutes and the result is noticeably creamier.

Serving Suggestions

Au Gratin Potatoes Recipe is a dish that I tend to make with our holiday dinner. Occasionally I make during the week as we enjoy it all year long. It is rich in flavor so we tend to have leftovers.

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