A simple French onion potato bake that uses Yukon potatoes, French onion soup mix, and Gruyere cheese to create a cheesy, creamy casserole!
Onion soup mix has a lot of uses. In fact, we have a French onion dip recipe that uses it as a spice blend.
For today, we're using that handy soup mix to create Kim's French onion potato bake.
As you can imagine, this side dish features cheesy, comforting potatoes flavored with those savory spices.
How to make a French onion potato bake with soup mix?
Creating this potato casserole isn't difficult, but it does have quite a few steps.
To make things easier, I separated out the instructions into sections.
That way, you can easily follow along with our directions. So, shall we get started?
Prep the Potatoes:
First, start by boiling the potatoes in a large stockpot filled with water. Use high heat for the quickest results.
The potatoes will need to boil for 12-15 minutes or until they're fork tender.
Meanwhile, preheat your oven to 350 degrees F. and grease an 8x8-inch square baking dish with non-stick cooking spray.
Once the potatoes are done, remove them from the heat and transfer them to an ice bath.
Let the taters chill until they're cool enough to handle.
Afterward, peel the potatoes and slice them into ½-inch circular pieces. Set them aside for now.
Make the Cheese Sauce:
Next, place a medium skillet over low-medium heat. Place the butter into the pan and let it melt.
After that, whisk in the flour and let it cook for 2-3 minutes to create your roux.
Now, while whisking continuously, pour in the heavy cream and milk. Go ahead and stir in the onion soup mix.
Then, when the liquid begins to steam, start adding the shredded Gruyere cheese.
I recommend sprinkling in 1 handful of cheese at a time. Whisk the mixture until the Gruyere has melted.
Continue the process until you've added all the shredded cheese to the sauce. Then remove the skillet from the heat.
Build the Casserole:
It's time to begin layering your potatoes, onions, and sauce into the baking dish. Kim placed ⅓ of each ingredient into every layer.
So, it goes sliced potatoes, onions, and then cheese sauce. Repeat the same process over and over again until the ingredients are gone.
Bake the Casserole and Serve:
To finish off the casserole, she added more shredded Gruyere cheese.
Last, place the potato bake into the oven (uncovered) and let it cook for about 30-minutes until the potatoes are cooked through.
Remove the casserole from the oven and let it cool for a few minutes before serving.
That's it, your French onion potato bake is done! Kim and I hope you enjoy it and wish you all the best 🙂
- If you don't have a digital kitchen scale, then 2 pounds of Yukon potatoes comes out to about 12 small potatoes or 6-8 medium potatoes.
- Whether you make 2 or 3 layers for this casserole is up to you. In fact, if you're using a large casserole dish, then you may only have 1-2 layers.
- The amount of layers in the dish may effect the baking time. Be sure to keep an eye on the casserole as it bakes; otherwise, it may scorch.
Don't forget to check out our Cheesy French Onion Potato Bake web story!
Recipe Card with Ingredient Amounts and Instructions
- 2 pounds gold potatoes
- 3 tablespoons unsalted butter
- 3 tablespoons all-purpose flour
- 1 cup heavy cream
- ½ cup whole milk
- 1 ounce onion soup mix, 1 packet
- 1 ½ cups Gruyere cheese, shredded off the block
- 1 ½ cups white onion, thinly sliced
- Preheat the oven to 350°F, and grease an 8 x 8, 9 x 9 - inch, or 2.5 quart baking dish. Set aside.
- Bring a large pot of lightly salted water and potatoes to a boil. Cook until the potatoes are just barely fork tender, about 12 to 15 minutes . Drain the water, and transfer the potatoes to an ice bath. When they’re cool enough to handle, gently remove the skins, and slice into ¼ - inch thick slices.2 pounds gold potatoes
- While the potatoes cook, make the sauce. Heat a medium skillet over low to medium heat. Add the butter, and allow it to melt. Once melted, add the flour. Whisk for 2 to 3 minutes, then while whisking, add the heavy cream and milk. Continue to whisk until smooth, then pour in the onion soup mix. Whisk to combine.3 tablespoons unsalted butter3 tablespoons all-purpose flour1 cup heavy cream½ cup whole milk1 ounce onion soup mix
- When the mixture begins to thicken slightly and steam, slowly begin to add 1 cup of the cheese, whisking between each addition. Remove from heat.
- Place a third of the potatoes into the baking dish, followed by a third of the onions. Top with a third of the cheese sauce. Repeat with the remaining potatoes, onions, and cheese sauce, then sprinkle the remaining ½ cup of cheese over the top.1 ½ cups white onion
- Bake uncovered for 25 to 30 minutes or until the potatoes are cooked through. Serve hot, and store leftovers in the refrigerator for 3 days.