These scalloped potatoes are SO good! You have layers of thinly sliced potatoes with a couple of layers of sautéed mushrooms, onions, and carrots. The whole thing is baked in a creamy white sauce.
This recipe comes from our acquaintances out west (Seattle area). I went out there with my sister for a friend’s wedding many-many years ago and this was served at the wedding (It’s that good!). Of course we wanted the recipe. Somehow, we forgot about the recipe for a couple of years, but as I came to study in Germany (and started cooking more on my own), this recipe was resurrected. It has been adjusted a bit over the years and I played with the sauce a lot to get it just right. So, here is my version of this wonderful, tasty dish.
Scalloped Potatoes Recipe
Prepping the Ingredients
Peel the potatoes and rinse them out in cold water. Slice the potatoes thinly using a mandoline slicer. If you don’t have a slicer, just use a good sharp knife to slice them. I usually slice them directly into the pot that I will use for cooking them (I have this set of pots and use the largest pot for this). Rinse the potatoes and then cover them with water and set aside.
Peel the onions and slice them thinly. I like to cut each half into fourths and then slice into thin stripes. Set aside.
Peel the carrots and grate them using a box grater. Transfer to a bowl and set aside.
Wash the mushrooms removing all dirt and then chop them. I usually like to cut them in half and then slice the halves into thin stripes.
Sautéing the vegetables
Heat a dutch oven or a heavy bottom pan and add some oil to it. Add the chopped onions to the pan and sauté until they are soft and translucent. Sprinkle with 1/8 tsp salt and pepper (to taste), mix well, and transfer to a separate bowl.
Add the carrots to the pan and sauté until they are soft (you might need to add another tablespoon of oil before adding the carrots). Sprinkle the carrots with 1/8 tsp salt and pepper (to taste), mix well, and add to the onions in the bowl.
Add the mushrooms to the frying pan and sauté until they give off liquid and all the liquid is cooked out. Sprinkle with 1/8 tsp salt and pepper (to taste), mix well, and add to the onions and carrots. Set the pot aside as we will make the sauce in it later (one less pot to wash 😊).
Once you’ve transferred the mushrooms to the bowl, mix all the sautéed vegetables together. Set aside.
You can also sauté these vegetables all together if your pot is big enough. Just start with the mushrooms and let the water cook out. Then add the onions and vegetables and sauté until ready.
Potatoes for Scalloped Potatoes 😄
Now for the potatoes. You can start on this part before you are fully done with sautéing the vegetables… Bring the potatoes to a boil and salt the water. Once the potatoes are boiling, reduce heat and let them simmer for about 5 minutes. The potatoes are thin and cook very quickly. However, they don’t need to be fully done. They will finish cooking in the sauce later.
Once the potatoes are done cooking, pour out the water by dumping the potatoes into a sieve, or just cover with the lid leaving a small slit, and use a towel to hold the lid and pour out the water (my way when I don’t want to dirty a sieve 😁).
Transfer half of the potatoes into a 9 x 13 casserole dish. Take half of the sautéed vegetables and spread them evenly on the top of the potatoes. Take the rest of the potatoes and place them on the vegetable layer spreading them as evenly as possible. Place the rest of the sautéed vegetables on the top of the potatoes. Set aside.
Preparing the Sauce
Now we will need to make a roux in order to make the sauce. Using the same saucepan that we used to sauté the vegetables, heat the oil. Add a heaping tablespoon of flour and whisk it until fully incorporated with the oil. Notice that I use a flat type of spatula for this part and not a whisk. This is because my pan is kind of squarish (not round) on the bottom and the whisk doesn’t get into the corners very well. This works very well for me. Use whatever works best for you.
Add heavy whipping cream to the flour and oil mixture a bit at a time. Make sure each addition is well incorporated into the mixture before adding more. Keep adding the cream until you have a thick sauce formed.
Once you have added all your cream and it is well incorporated and you have a thick creamy sauce, add the milk to the mixture a bit at a time. Mix well, before each addition.
Add salt and pepper and any herbs (if desired). It doesn’t need any herbs, but sometimes I like to add dry basil or something like that.
If you want to learn all about the roux and see a video for making it, I recommend this helpful article and video from the Spruce Eats: How to Make Roux.
Baking Scalloped Potatoes
Preheat the oven to 350 °F. Pour the sauce over the potatoes and spread evenly with a spatula, if needed. Cover with foil and bake for 40 minutes. Meanwhile, shred some cheese if you didn’t buy the shredded kind.
Take out scalloped potatoes from the oven and sprinkle with shredded cheese. Place back into the oven and bake an additional 10 minutes or until the cheese has melted and starts to brown.
And just like that, your scalloped potatoes are done! Let these rest 10 minutes or so, that is, if you can wait that long. I usually just like to dig in. But I have to say the dish tastes even better the next day when it has stood a while. The flavors just come together awesomely!
Scalloped Potatoes Prep
- 3lb 4oz (1.5kg) Potatoes
- 14oz (400g) Portobello mushrooms
- 2 Medium onions
- 3 Medium carrots
- 9oz (250g) Cheese, Mozzarella or Gouda (or to taste)
- 5-6 tbsp Olive Oil
- ⅜ tsp Salt (Plus extra for cooking potatoes)
- Pepper to taste
- 1 tbsp Flour (heaping)
- 2 tbsp Olive oil (or other vegetable oil, or butter)
- 2 ½ cups Heavy whipping cream
- 1 ½ cups Milk
- 1 ¼ tsp Salt
- ⅛ tsp Pepper (or to taste)
- Peel the potatoes and slice them using a Mandoline slicer. Transfer to a pot and fill with water. Set aside.
- Wash and peel (as needed) the onions, carrots and mushrooms. Chop the mushrooms and the onions and grate the carrots using a box grater.
- Add a bit of olive oil into a skillet or heavy bottomed pan/pot and sauté the onions until soft and translucent. Add ⅛ tsp salt and pepper (to taste). Transfer to a separate bowl.
- Add some more oil to the pan (if needed) and proceed to sauté the carrots and the mushrooms, one after the other. Allow the water to cook out when sautéing the mushrooms. Salt each vegetable with with ⅛ tsp salt and pepper as needed. Transfer the sautéed vegetables to the onions and mix everything together. Set aside.
- Meanwhile, salt the potatoes and bring the to a boil. Cook for about 5 minutes. They do not need to be fully done as they will finish cooking with the sauce.
- Once the potatoes are done, pour out the cooking water and spread half of the potatoes into a 9 x 13 baking dish.
- Layer half of the sautéed vegetables on the top of the potatoes. Then do another layer of the potatoes and the vegetables. Set the dish aside.
- Preheat the oven to 350°F (180°C).
- Heat the oil in a pan (I used the same one that I used for sautéing the veggies). Add flour and mix constantly allowing the flour to brown a bit. Slowly add the heavy whipping cream a bit at a time. Make sure each addition is well-incorporated.
- Once the cream is all added and you have a thick sauce formed, slowly add the milk, whisking and mixing all the while. Once all the milk is added and a good sauce is formed, season with salt and pepper.
Baking Scalloped Potatoes
- Pour the sauce over the potatoes. Cover with foil and bake 40 minutes in the oven.
- Meanwhile, shred the cheese.
- Take out the potatoes from the oven and sprinkle with shredded cheese. Bake an additional 10 minutes without foil.
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