Thinly sliced au gratin potatoes recipe with onions, garlic, and thyme in a creamy white cheese sauce baked to bubbly perfection.
Potatoes of all kinds show up on our dinner table more than once a week. This easy au gratin potatoes recipe is a favorite of everyone, even the kids. While it's something you need to think about ahead of time, it's still at the top of the list for sides. All that creamy, cheesy goodness is hard to pass up. If you haven't tried making this yet, you're going to want to give it a go!
Au gratin is a French culinary term defined as a dish that is topped with breadcrumbs or cheese and browned on top. Some other examples of this include vegetables and fish. The potatoes in this dish are sliced thin and coated with a cheese sauce that includes softened onions, garlic, and fresh thyme leaves. It's then topped with more cheese and baked, covered, for 30 minutes, then uncovered for another 20 - 25 or until golden.
One of the best tools you can use for this dish is a mandoline, although a chef's knife will work as well. You can see a review of the Prepworks by Progressive Mandoline I've done if you're wondering if this is a good purchase for you. Personally, I love it. It makes slicing so many different things that much easier.
How to make au gratin potatoes
- cheese grater
- Cutting board
- Chef's knife
- large bowl
- 2 pounds Yukon potatoes
- 1/4 cup butter
- 1/2 white onion diced
- 3 garlic cloves minced
- 1/3 cup all-purpose flour
- 1 cup whole milk
- 1 cup heavy cream
- 2 cups white cheddar shredded
- 1 teaspoon salt
- 1/2 teaspoon pepper
- 2 teaspoons fresh thyme leaves
- Preheat the oven to 400°. Peel and thinly slice the potatoes with a mandoline or chef's knife. Dice the onion, mince the garlic, and grate the cheese. Grease a 9x13 inch casserole dish.
- Heat a saucepan on medium-low and add the butter, onions, and garlic. Sauté until soft, about 3 minutes. Cover with the flour, stir and allow to cook for 2 more minutes.
- Pour in the milk, cream, salt, pepper, and thyme and allow to simmer for about 5 minutes, or until it starts to thicken. Remove from the heat and add the cheese. Stir to combine until it all melts into a cheesy sauce.
- Put the sliced potatoes in a large bowl and slowly pour the cheese sauce over the top. Stir until all the potatoes are covered in the sauce. Pour this in the casserole dish, cover with aluminum foil, and bake for 30 minutes. Remove the foil and cook for an additional 25 minutes.