Oh My Goodness! This recipe for creamy mushroom and potato au gratin is a must make this year.
Don’t tell anyone, but up until a couple of years ago, I didn’t like potatoes. I know you are thinking, “What is wrong with her!”
Sorry!
When I was growing up, my dad owned a potato farm. My very first job in life was working on a sorting line on the potato farm. I saw so many potatoes over a couple of summers that I never wanted to see another one ever again.
EVER!
How to Make Creamy Mushroom and Potato Au Gratin
Let’s get started, shall we?

First, preheat the oven to 375 F degrees. While the oven is preheating, slice eight ounces of fresh mushrooms. I used baby Bella, but any mushrooms should work.
While you have the cutting board out, go ahead and dice up one half of an onion and mince three cloves of garlic.
Thinly slice two and a half pounds of red potatoes approximately 1/8″ inch thick. I leave the skin on, but that is a personal preference. I slice my potatoes on a mandolin for uniform thickness. The mandolin is one of my most used kitchen gadgets.
Next, melt three tablespoons melted butter in a medium saucepan on medium-high heat. Add in the sliced mushrooms, onion, and minced garlic.
Continue cooking until mushrooms are tender, approximately five minutes. Then add in one and one half tablespoon flour, one teaspoon salt, one teaspoon pepper, and one teaspoon thyme then mix well. Cook for an additional two minutes stirring constantly.
Slowly add in one and one-half cups of milk, continually whisking until smooth. Then mix in one and one-half cups of heavy cream and bring to a simmer. Allow to simmer for one minute and remove from heat. Whisk in seven ounces (this was how much is in the package that I buy) of shredded Gouda. I love shredding my cheese with an attachment for my stand mixer.
Next, layer the sliced potatoes in a 9×13 inch baking dish. Pour the cream of mushroom sauce over the potatoes. Bake the potato and mushrooms for ninety minutes at 375 F degrees.
There you have it, my favorite mushroom and potato recipe with so much creamy cheese, oh my.
BOOM! Now you are going to be the hero of your next get together.
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More Traditional Side Dishes
If you are looking for more traditional side dishes for a potluck or holiday meal, be sure to try this old fashioned macaroni and cheese. This is the ultimate mac and cheese recipe with three types of cheese and a panko bread crumb flavorful topping.
If You Love Potatoes
If you are a potato lover like my husband, take a look at my slow cooker loaded potato soup. Throw a few ingredients in the slow cooker in the morning and the Crock-Pot basically cooks dinner for you.

Mushroom And Potato Au Gratin
This cheesy, creamy mushroom and potato bake is the best casserole dish recipe you will ever need. This recipe is loaded with fresh mushrooms, potatoes, and gouda cheese — comfort food at its best.
Ingredients
- 2 1/2 pounds red potatoes
- 8 ounces fresh mushrooms
- 1/4 diced onion
- 3 cloves garlic
- 1 teaspoon salt
- 1 teaspoon black pepper
- 1 teaspoon fresh Thyme
- 1 tablespoon flour
- 1 1/2 cup milk
- 1 1/2 cup heavy cream
- 7 ounces Gouda
Instructions
- Preheat oven to 375 F degrees.
- Slice 8 ounces of fresh mushrooms, dice 1/2 an onion, and mince 3 cloves of garlic.
- Thinly slice 2 1/2 pounds red potatoes to 1/8″ thick.
- Melt 3 tablespoons butter in a medium saucepan on medium-high heat. Add in mushrooms, onion, and garlic. Cook until mushrooms are tender.
- Stir in 1 1/2 tablespoon flour, one teaspoon salt, one teaspoon pepper, and one teaspoon thyme then continue stirring for two minutes.
- Slowly whisk in 1 1/2 cups milk, mixing well until smooth. Then slowly add in 1 1/2 cups heavy cream and while stirring constantly, bring to a slow simmer.
- Remove from heat and whisk in 7 ounces of shredded Gouda cheese.
- Layer the sliced potatoes in a 9×13 inch baking dish. Pour the mushroom mixture over the potatoes and bake at 375 F degrees for 90 minutes.
Notes
- I used baby Bella mushrooms, but white mushrooms would work fine.
- I do not peel my potatoes, but this is a personal preference. You can peel them if preferred.
Nutrition Information:
Yield: 10 Serving Size: 1Amount Per Serving: Calories: 324Total Fat: 19gSaturated Fat: 12gTrans Fat: 0gUnsaturated Fat: 6gCholesterol: 66mgSodium: 417mgCarbohydrates: 28gFiber: 3gSugar: 4gProtein: 11g
All information and tools within this site are intended for informational purposes only. I am not a certified nutritionist and any nutritional information on swingshiftmom.com should only be used as a general guideline. This information is provided as a courtesy and there is no guarantee that the information will be completely accurate. The nutritional labels are a product of online calculators. Even though I try to provide accurate nutritional information, these figures should be considered estimates.