Caramelized Onion Sheet Pan Scalloped Potatoes
Listen I know that’s a long title but all of these words are crucial! The caramelized onions - oh my gahh. So insanely good and rich. And on a sheet pan? Think of all those crispy, cheesy edges. Scalloped potatoes? Creamy and gooey and layered and gahhhhh… the star of the Thanksgiving table.
Have I mentioned how much I love potatoes?
So here’s what we’re gonna do. You’re going to get your onions rolling in the pan. Slice them up nice and thin and add them to a pan on low with some butter. Top them with a hearty shake of thyme and rosemary, a bit of salt and pepper, and let those puppies work their magic while you move onto your next task.
Slice up your potatoes and get them soaking in a cold water bath which will prevent them from browning. Final step before assembly is getting your cheese sauce together. I like to utilize my food processor for this step, but the most important thing here is to not use pre-grated cheese. As soon as your onions are nice and caramelized, remove them from a pan and start on your roux. A roux is equal parts butter and flour and is used to thicken a sauce. Once you’ve combined the roux, drizzle in the milk. Season the sauce with your spice mixture and then slowly mix in the grated cheese. Allow this to get nice and bubbly, then start to assemble. Bake those babies and then the real challenge comes… Don’t eat all of the edges before you serve! Impossible, I know. But try your hardest. Here’s the full details. Promise me you’ll come back and tell me how much you loved these. :)
CARAMELIZED ONION SHEET PAN SCALLOPED POTATOES
Prep time: 30 minutes
Bake time: 25 minutes
Ingredients:
3 large white onions, thinly sliced
4 T butter, separated
1 T thyme
½ T rosemary
Salt and pepper, to taste
1 T brown sugar
4 large russet potatoes, scrubbed and thinly sliced
2 T flour
1½ cups freshly grated sharp cheddar or gruyere
2 cups milk
1 t ground mustard powder
1 t garlic powder
Directions:
Preheat your oven to 375.
1.) Thinly slice the onions and place in a pan above low heat, with 2 tablespoons of butter. Sprinkle with thyme, rosemary, salt and pepper. Allow the onions to cook, stirring occasionally, for 20-30 minutes. Towards the end of their cooking time, add in a tablespoon of brown sugar. The brown sugar isn’t necessary as onions release their sugars as they cook, but I like to add a bit of additional sweetness to temper our all the salt from the rest of the dish.
2.) While the onions are cooking, begin to prep your potatoes. Slice them into rounds and place into a water bath to prevent them from browning.
3.) Grate the cheese to begin the cheese sauce. As soon as the onions are soft, brown, gooey and delicious, remove them from the pan and set aside. Add the remaining 2 T of butter to the pan and mix with 2 T of flour. Slowly drizzle in the milk, stirring constantly until you have a congruent mixture. Pour in the mustard powder, garlic powder, and additional salt and pepper. Dump in your cheese and mix until thick, hot and bubbly.
4.) Assemble the dish on a sheet pan. Potatoes, onions, cheese sauce, repeat. Top with a light sprinkle of salt and black pepper, then bake for 20-30 minutes until the potatoes are cooked through and the top is bubbly and brown.
I love burnt cheese more than I love my own children, so I like to broil for 30 seconds at the end. But this is optional, and if you go this route, make sure your morning Thanksgiving mimosa doesn’t distract you. We want brown and golden, not burnt!
