This Mushroom Gruyère Grilled Cheese features three varieties of mushrooms, sautéed leeks, roasted Yukon gold potatoes, and two delectable cheeses, all griddled between slices of artisan bread enhanced by the addition of thyme-infused butter. Now that's a grilled cheese!
(This recipe was originally published in April 2016, but was updated with new photos and content in 2022).
Grilled cheese can be much more sophisticated than toasty white bread stuffed with molten American cheese. Case in point, this mushroom grilled cheese has most unbelievable combination of flavors and textures.
The bread is audibly crunchy, while the potatoes are soft, creamy and simply melt-in-your-mouth. Meanwhile, the mushrooms boast a great umami flavor with an assist from the thyme (a fantastic complement to mushrooms).
Tender leeks provide mild onion notes, while the duo of alpine cheeses (Gruyère and Fontina Val d’Aosta) are truly the cherry on this figurative sundae. They're stretchy and gooey, quite literally holding the entire sandwich together.
The combination reminds me a bit of cheesy potatoes au gratin enhanced with earthy mushrooms, served in a crunchy, hand-held package.
Using premium ingredients is really key for making a stellar grilled cheese. One of the specialty cheeses called for in this mushroom grilled cheese recipe may be a bit more challenging to source, but you can easily swap it for a more available alternative.
Ingredient notes
- Bread: Do not use standard sandwich bread (you know, the soft squishy stuff) for these mushroom grilled cheese sandwiches. You need a heartier rustic artisan style loaf with a firm crumb, such as Levain or sourdough. I use a Tuscan style bread in these photos.
- Gruyère Cheese: Gruyère is a hard Swiss cheese best known as the gooey topping for French Onion Soup. It's sharp, nutty, complex, and a fantastic melting cheese for grilled cheeses.
- Fontina Cheese: Fontina cheese was first produced in Italy, but has spread to worldwide production including in the United States, Denmark, Sweden, etc. The original Fontina cheese from the Aosta Valley in Italy is a pale cream color, has some "eyes" (aka holes) and has an earthy, buttery flavor. It pairs well with the sharper and more assertive Gruyère for these sandwiches. Other styles of Fontina from outside of Italy are much milder, paler, and often feature a red wax rind (see the photos below). Fontina Val d’Aosta may be harder to find, as most American grocery stores will sell the other variety, but I have found the Italian version at Whole Foods and at dedicated cheese shops. In a pinch, you can use other types of Fontina, but it's worth the extra effort to find Fontina Val d’Aosta if you can.
- NOTE: These cheeses are typically made with animal rennet which means they aren't vegetarian. If you're vegetarian, use a vegetarian version. Boar's Head brand makes vegetarian Gruyère and Fontina cheeses you could use.
- Mushrooms: There are 3 varieties of mushrooms in this exquisite mushroom grilled cheese recipe. You'll need shiitake, cremini (baby portabella), and oyster mushrooms, though you can easily swap any of those out for other types. It's best to use a variety in any case, rather than a single type.
- Potato: It may seem odd adding roasted potatoes to a grilled cheese sandwich, but the creamy texture and buttery flavor of Yukon golds really help elevate these sandwiches. Using other potatoes, such as floury white baking potatoes will not yield the same effect. I highly recommend seeking out yellow or gold potatoes for optimal results here.
How to make it
In a small bowl, stir together the soft butter and half of the thyme until smooth. Set aside.
Toss sliced potatoes with olive oil and a pinch each of salt and pepper. Arrange the potatoes in a single layer on a parchment paper lined baking sheet and roast until cooked through and starting to brown in spots (PHOTOS 1-2). Set aside to cool.
In a small saucepan over medium-low heat, heat olive oil. Add chopped leek along with a pinch of salt and stir to lightly coat. Cover and cook, stirring to prevent sticking, until the leek is very soft. Remove from the heat and set aside.
In a medium sauté pan over medium-high heat, heat olive oil, then add all of the mushrooms, thyme, and a pinch each of salt and pepper. Sauté until the mushrooms have released their juices, are tender, and are just beginning to brown. Set aside.
Spread the thyme butter on one side of each bread slice, dividing it evenly. Place two slices, buttered side down, on a clean cutting board.
Spread about 2 tablespoons of the sautéed leeks on each slice of bread. Top each slice of bread with half the sliced fontina, half of the potatoes (PHOTO 3), and half of the cooked mushroom mixture (PHOTO 4).
Finish by arranging half the sliced Gruyère on top of each.
Top with the remaining bread slices, buttered side up. Be careful handling the uncooked sandwiches, as they may be quite full. If anything falls out, just tuck the fillings back inside. I recommend using a large spatula to move them.
Heat a large nonstick skillet over low heat. Using a large spatula, place both sandwiches in the skillet, cover with a lid, and cook until the bottoms are nicely browned. Turn and cook until the second sides are browned and the cheese is melted.
Cut the mushroom grilled cheese sandwiches in half, if desired, and serve immediately.
Please scroll to the bottom of the post for the full recipe (in a printable recipe card) including ingredient amounts and detailed instructions.
Expert tips
To flip these mushroom grilled cheese sandwiches I recommend removing them from the skillet one by one with a large spatula and placing on a plate. Then place an inverted plate on top, flip the whole thing over, then use the spatula to move the flipped sandwiches from the plate back to the hot skillet. This will yield the least messy results and none of the filling should fall out.
You may have leftover sautéed leeks (depending on the size of the leek you started with). I like stirring leftovers into mashed potatoes or adding them to soup.
To make ahead, you can cook all of the components (the potatoes, leeks, and mushrooms), slice the cheeses, and refrigerate for a couple days until you're ready to use them. Then, assemble and cook as directed.
I would not recommend making these mushroom grilled cheese sandwiches in advance. Make them right before you plan to enjoy them. If you have any leftovers, however, you can reheat them in a toaster oven, or in a skillet over a low flame until crispy and heated through, flipping over halfway.
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Mushroom Gruyère Grilled Cheese
Ingredients
- 2 tablespoons butter at room temperature
- 1 teaspoon minced fresh thyme or ½ teaspoon dried thyme
- 1 small Yukon gold potato, peeled and cut into slices about ¼-inch thick
- 2 ½ teaspoons olive oil
- Kosher salt and freshly ground black pepper
- 1 small leek (or ½ large leek), trimmed and tough green tops removed, halved lengthwise and carefully washed, cut into ¼-inch dice
- 2 ounces (55 grams) shiitake mushrooms, stemmed, brushed clean, and cut into slices about ⅛-inch thick
- 2 ounces (55 grams) cremini mushrooms, brushed clean and cut into slices about ⅛-inch thick
- 2 ounces (55 grams) oyster mushrooms, brushed clean and coarsely chopped
- 4 slices rustic artisan bread such as levain, sourdough, or white
- 3 ounces (85 grams) sliced Italian-style fontina cheese (preferably Fontina Val d’Aosta)
- 3 ounces (85 grams) sliced Gruyère cheese
Instructions
- Preheat the oven or toaster oven to 425°F. Line a small baking sheet with parchment paper or coat thoroughly with nonstick cooking spray.
- In a small bowl, stir together the soft butter and half of the thyme until smooth. Set aside.
- In a medium bowl, toss the potatoes with ½ teaspoon of the olive oil and a pinch each of salt and pepper until the potatoes are evenly coated. Arrange the potatoes in a single layer on the prepared baking sheet and roast until cooked through and starting to brown in spots, about 15 minutes, flipping over about halfway through. Set aside to cool.
- Meanwhile, in a small saucepan over medium-low heat, heat 1 teaspoon of the olive oil. Add the leek along with a pinch of salt and stir to lightly coat. Cover and cook, stirring to prevent sticking, until the leek is very soft, about 10 minutes. Remove from the heat and set aside.
- Meanwhile, in a medium sauté pan over medium-high heat, heat the remaining 1 teaspoon olive oil. Add all of the mushrooms, the remaining thyme, and a pinch each of salt and pepper. Sauté until the mushrooms have released their juices, are tender, and are just beginning to brown, about 3 to 5 minutes. Set aside.
- Spread the thyme butter on one side of each bread slice, dividing it evenly. Place two slices, buttered side down, on a clean cutting board.
- Spread about 2 tablespoons of the sautéed leeks on each slice of bread. Top each slice of bread with half the sliced fontina (1 ½ ounces / 42 grams), half of the potatoes, half of the cooked mushroom mixture, and finish by arranging half the sliced Gruyère (1 ½ ounces / 42 grams) on top of each.
- Top with the remaining bread slices, buttered side up. Be careful handling the uncooked sandwiches, as they may be quite full. If anything falls out, just tuck the fillings back inside. I recommend using a large spatula to move them.
- Heat a large nonstick skillet over low heat. Using a large spatula, place both sandwiches in the skillet, cover with a lid, and cook until the bottoms are nicely browned, about 6 to 8 minutes. Turn and cook until the second sides are browned and the cheese is melted, about 4 to 6 minutes longer.
- Cut the sandwiches in half, if desired, and serve immediately.
Notes
- To flip these sandwiches I recommend removing them from the skillet one by one with a large spatula and placing on a plate. Then place an inverted plate on top, flip the whole thing over, then use the spatula to move the flipped sandwiches from the plate back to the hot skillet. This will yield the least messy results and none of the filling should fall out.
- To make ahead, you can cook all of the components (the potatoes, leeks, and mushrooms), slice the cheeses, and refrigerate for a couple days until you're ready to use them. Then, assemble and cook as directed.
- Italian Fontina Val d’Aosta may be harder to find, as most American grocery stores will sell another variety (domestic or often from Swedish or Denmark), but I have found the Italian cheese at Whole Foods and at dedicated cheese shops. In a pinch, you can use other types of Fontina, but it's worth the extra effort to find Fontina Val d’Aosta if you can.
- These cheeses are typically made with animal rennet which means they aren't vegetarian. If you're vegetarian, use a vegetarian version. Boar's Head brand makes vegetarian Gruyère and Fontina cheeses you could use.
- You may have leftover sautéed leeks (depending on the size of the leek you started with). I like stirring leftovers into mashed potatoes or adding them to soup.
- Adapted from Grilled Cheese Kitchen
Nutrition
*All nutritional information is based on third-party calculations and should be considered estimates. Actual nutritional content will vary with brands used, measuring methods, portion sizes and more.*
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