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.
1teaspoonminced fresh thyme or ½ teaspoon dried thyme
1small Yukon gold potato,peeled and cut into slices about ¼-inch thick
2 ½teaspoonsolive oil
Kosher salt and freshly ground black pepper
1small leek (or ½ large leek),trimmed and tough green tops removed, halved lengthwise and carefully washed, cut into ¼-inch dice
2ounces(55 grams) shiitake mushrooms,stemmed, brushed clean, and cut into slices about ⅛-inch thick
2ounces(55 grams) cremini mushrooms,brushed clean and cut into slices about ⅛-inch thick
2ounces(55 grams) oyster mushrooms,brushed clean and coarsely chopped
4slicesrustic artisan bread such as levain, sourdough, or white
3ounces(85 grams) sliced Italian-style fontina cheese(preferably Fontina Val d’Aosta)
3ounces(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.