This au gratin potatoes recipe is one of my favorite holiday dishes. This version has butternut squash in the layers in addition to Yukon gold potatoes, adding a nice subtle sweetness.
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How to customize this au gratin potatoes recipe
- If you are not a fan of butternut squash, simply use all Yukon gold potato instead.
- You could use sweet potatoes instead of butternut squash or the Yukon golds.
- Add bacon or ham if you’re an omnivore. Add the cooked and chopped protein on top of the potatoes before pouring the sauce over!
- Top with some breadcrumbs on top for a bit of crunch. We like toasted panko breadcrumbs in this situation. They tend to have more texture and get crispier in the oven. Just toast them in a dry skillet over medium-low heat until they begin to turn a little golden and become fragrant.
- Make this recipe vegan by using your favorite non-dairy cheese, dairy-free milk, and vegan butter. The texture will be a bit different, of course, but it will taste great. A little bit of nutritional yeast can also help replace the tang of regular cheese.
- Use fresh thyme instead of dried thyme. Substitute rosemary if desired, but thyme is more traditional. You can also add a some chopped fresh parsley to the breadcrumbs if you want a little extra flavor.
- Swap out other types of squash if desired such as longneck squash or Kabocha or another orange-fleshed squash.
Can you make this recipe ahead of time?
Yes! If you want to prep this recipe ahead of time, you absolutely can. You can do in a few different ways. Prep all the potatoes and squash and cover them in little bit of cold water. Store in the fridge, covered, overnight. Then take them out, drain off the water and pat dry, and assemble as directed.
Or, you can make the entire dish ahead of time cover it with foil after the sauce has been added and place the dish in the fridge. You prep this up to 3 days before baking! When you bake, either allow the dish to come to room temperature before putting it in the oven, or add on 15-20 minutes to the cook time, since it will be cold.
What is the difference between au gratin potatoes and scalloped potatoes?
These two dishes are incredibly similar, but not the same! Scalloped potatoes are simpler – they are typically just potatoes cooked in a cream sauce; it doesn’t typically have cheese. Often but not always the potatoes are cut a little thicker; for au gratin, potatoes are sliced thinly and the top layer gets crispy.
To assemble, au gratin potatoes are made by sprinkling cheese over layers of potatoes and baking it all in a Mornay sauce; a combination of a roux (or bechamel) and cheese. It sounds fancy but it’s not hard. If you have ever make mac and cheese from scratch you can definitely make au gratin potatoes.
In our case here, we’re making a gratin with squash instead of potatoes and the whole dish is baked in that cheese sauce. Either of these types of potato preps are delicious and comforting.
One other small note: gratin recipes are typically made in a more shallow, oval dish but you can use any dish you have on hand for this recipe. Scalloped potatoes tend to do well in traditional 2 and 3-quart rectangular casserole dishes.
What is the best cheese for au gratin potatoes?
We used sharp cheddar and parmesan, but if you want to mix things up you can use jack, pepper jack, gruyere, or your favorite non-dairy cheese!
How to store and reheat au gratin potatoes
This meal will last in the fridge for up to 4 days, and can be reheated in the microwave or the oven. We prefer the oven for this dish because it enables the top of the gratin to crisp up again. It’s also freezer-friendly for up to six months. Enjoy!
And don’t forget to try our other delicious holiday recipes!
- Vegan Pot Pie Pockets
- Brussel Sprout Caesar Salad
- Stuffed Shells With Spinach
- Spinach and Artichoke Dip
- Stuffed Mushrooms
- Mini Pineapple Upside Down Cakes
- Easy Carrot Cake Recipe
- The Best Chocolate Pecan Pie
Cheesy Au Gratin Potatoes Recipe
Ingredients
- 2 lbs Yukon gold potatoes sliced thinly
- 8 oz butternut squash sliced thinly
- 1/2 yellow onion diced small
- 2 garlic cloves minced
- 3 TBSP butter
- 3 TBSP flour
- 16 oz milk of your choice
- 1 tsp salt divided, plus more to taste
- 1/4 tsp pepper plus more to taste
- 1/4 tsp dried thyme or 1 tsp fresh, minced
- 8 oz shredded cheese sharp cheddar, Gruyere, or Gouda
- 4 oz Parmesan cheese grated, or Romano
Instructions
- Heat oven to 400 F (200 C). Butter or spray a baking dish or ovenproof skillet.
- Layer slices of potatoes and butternut squash along the bottom of the dish (I overlapped the rows a little bit). Sprinkle a little salt and pepper over the layer, then top with the onions and garlic. Add another layer of potatoes and squash and add another sprinkle of salt and pepper. Set aside. (You can add a little bit of grated Parm here in between the layers if you like, but it's not necessary).
- In a medium saucepan, melt the butter. Add the flour and stir together until fully incorporated, making a roux (paste). Cook forĀ 2-3 minutes. Slowly add the milk and whisk together to prevent lumps. Add the salt, pepper, and thyme and stir. Add all of the shredded cheese and stir until melted fully. Taste and see if it needs more salt. Keep in mind that potatoes can handle A LOT of salt, but Parm has a bit of a salty tang, too.
- Pour the cheese sauce evenly over the potato/squash layers and top with the Parmesan. Cover the dish tightly with aluminum foil and bake for 60-75 minutes until the potatoes are fork-tender. Remove the foil and broil for 2-5 minutes (keep a close eye on it!) until the cheese is golden-browned to your preference.
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