Cheesy Au Gratin Potatoes (Easy Make-Ahead Christmas Side)
If there’s one side dish that disappears first at my holiday table, it’s anything with potatoes and lots of cheese. These cheesy au gratin potatoes are the best of both.
Thin potato slices are layered with a creamy homemade cheese sauce made with sharp cheddar and Gruyere. Then the whole dish gets a thick blanket of cheese on top and bakes until golden, bubbly and crisp around the edges.
I make these every Christmas because they’re cozy, they feed a crowd and they can be assembled a day ahead. That’s a big win when the oven is busy.
Why You’ll Love These Au Gratin Potatoes
- Extra cheesy. Three cheeses in the sauce and on top.
- Golden, crispy top. Baking uncovered at the end gives a bubbly crust.
- From scratch. No boxed mix or canned soup.
- Make-ahead. Assemble the day before.
- Crowd favorite. Kids and adults both go back for seconds.
Ingredients You’ll Need
The exact amounts are in the recipe card at the end of this post. Here’s a quick guide.
- Potatoes: Yukon Gold are creamy and hold their shape. Russets also work well.
- Sharp cheddar: Brings bold cheesy flavor. Shred it yourself so it melts smoothly.
- Gruyere: Nutty and melty. Swiss cheese or more cheddar is a fine swap.
- Parmesan: Helps the top turn golden and crisp.
- Butter, flour, milk and cream: The base of a smooth cheese sauce that won’t break.
How to Make Au Gratin Potatoes
- Prep. Heat the oven to 400°F (200°C) and slice the potatoes 1/8 inch thick.
- Make the cheese sauce. Cook garlic in butter, whisk in flour, then milk and cream. Stir in seasoning and half the cheddar and Gruyere.
- Layer. Layer potatoes and sauce in a buttered 9×13 dish, in two layers.
- Bake covered. Cover with foil and bake 45 minutes.
- Add the cheese top. Uncover, add the rest of the cheese and bake 25 to 30 minutes, until golden. Rest 15 minutes.
My Tips for the Best Au Gratin Potatoes
- Shred your own cheese. Bagged shredded cheese has coatings that can make the sauce grainy.
- Warm the milk first so the sauce stays smooth and thickens faster.
- Take the sauce off the heat before adding cheese so it melts gently.
- Use a mandoline for even slices, and always use the hand guard.
- Let it rest. Cutting in right away makes the sauce runny.
Variations to Try
- Bacon: Add crumbled cooked bacon between the layers.
- Spicy: Use pepper jack instead of Gruyere.
- Herby: Add fresh thyme or chives to the sauce.
- Crunchy top: Sprinkle buttered panko over the cheese for the last 15 minutes.
Make-Ahead, Storage and Reheating
- Make ahead: Assemble without the top cheese up to 1 day ahead. Refrigerate and add 15 minutes to the covered baking time.
- Storage: Refrigerate leftovers within 2 hours for up to 4 days.
- Reheat: Cover and warm at 350°F (175°C) for 20 to 25 minutes.
What to Serve With It
These cheesy potatoes are amazing next to a big holiday roast. Try them with my Prime Rib Roast for Beginners, plus green beans or a crisp salad to keep the plate balanced.
Frequently Asked Questions
What does au gratin mean? It means a dish topped with cheese or breadcrumbs and baked until golden and crisp on top.
Do I need to boil the potatoes first? No. Thin slices cook fully in the oven as long as you cover the dish for the first part of baking.
Why is my cheese sauce grainy? The sauce was too hot when the cheese went in, or the cheese was pre-shredded. Melt freshly shredded cheese off the heat.
Can I make it in a smaller dish? Yes. Halve the recipe and use an 8×8-inch dish. Start checking about 10 minutes sooner.
One Last Thing
These cheesy au gratin potatoes are the cozy side dish every holiday meal needs. If you make them, please leave a comment and a star rating below. And save the recipe to your Christmas dinner board on Pinterest!
Cheesy Au Gratin Potatoes
Ingredients
Potatoes:
- 3 lb Yukon Gold or russet potatoes peeled and sliced 1/8 inch thick
Cheese sauce:
- 4 tbsp butter
- 2 cloves garlic minced
- 1/4 cup all-purpose flour
- 2 1/2 cups whole milk warmed
- 1/2 cup heavy cream
- 1 1/2 tsp kosher salt
- 1/2 tsp black pepper
- 1/4 tsp smoked paprika
Cheese:
- 2 cups sharp cheddar freshly shredded, divided
- 1 cup Gruyere freshly shredded, divided
- 1/2 cup grated Parmesan
Instructions
- Heat the oven to 400°F (200°C). Butter a 9×13-inch baking dish.
- Melt the butter in a saucepan over medium heat. Add the garlic and cook 30 seconds. Whisk in the flour and cook 1 minute.
- Slowly whisk in the warm milk and cream. Simmer, whisking, until thick enough to coat a spoon, 3 to 5 minutes. Remove from the heat and stir in the salt, pepper, paprika, 1 cup cheddar and 1/2 cup Gruyere until smooth.
- Layer half the potatoes in the dish. Pour half the sauce over them. Add the rest of the potatoes and the rest of the sauce, pressing the potatoes down into the sauce.
- Cover with foil and bake for 45 minutes. Uncover, top with the remaining cheddar, Gruyere and the Parmesan, and bake 25 to 30 minutes more, until the potatoes are tender and the top is golden and bubbly.
- Rest 15 minutes before serving so the sauce sets.
Notes
Storage: Refrigerate leftovers within 2 hours for up to 4 days.
Reheat: Cover and warm at 350°F (175°C) for 20 to 25 minutes.
Variations: Use all cheddar, add crumbled bacon between the layers, or add sliced green onions on top.
