- 4-6 medium yukon gold potatoes, thinly sliced into 1/8th inch rounds
- ½ white or yellow onion, cut into slices
- 2 tablespoons salted butter
- ¼ cup all purpose flour
- 1 1/2 cups whole milk
- 8 ounces sharp cheddar cheese
- ½ teaspoon garlic powder
- ¾ teaspoon salt, plus more to taste
- Freshly ground black pepper
- Preheat the oven to 375 degrees F. Spray a 2 quart square baking dish (or an 8×12 is good) with nonstick cooking spray or grease with butter or oil.
- Place sliced potatoes in three tight slanted rows as indicated in the photos. You don’t want them to be overly tight, make sure you leave enough space so the potato slices are slightly slanted. Add in onion slices in between the rows and on top of potatoes. Basically wherever you can fit them.
- Next make your sauce: add in 2 tablespoons of butter and place over medium heat. Once butter is melted, whisk in a little bit of the flour and then slowly add in milk, a little bit at a time, alternating with the flour and vigorously whisking away any lumps. Bring mixture to a simmer; it should be a similar consistency to creamy gravy.
- Turn heat to low and stir in shredded cheddar cheese, garlic powder, salt and pepper. Taste and add more salt and pepper, if necessary.
- Pour the sauce evenly over the potatoes and onions to cover them. Don’t worry, the sauce will get nice and creamy while baking.
- Bake for 45 minutes. Enjoy!