Save The smell of butter browning in a cast iron skillet always takes me straight back to rainy afternoons when nothing else would do but something warm and melty. I was experimenting one Saturday, tired of the same old cheddar on white, and spotted a handful of mushrooms in the crisper that needed using. What started as fridge clean-out became my most requested sandwich. Now I keep rye bread and Swiss on hand just in case the craving hits, which happens more often than I'd like to admit.
I made this for my neighbor once after she helped me move furniture, and she stood in my kitchen eating it over the sink because she didn't want to wait for a plate. She kept saying she couldn't believe it was just mushrooms and cheese. That's when I realized this sandwich had something special going on, something that made people slow down and actually taste what they were eating. It's become my go-to whenever I want to show someone I care without making a big production out of it.
Ingredients
- Cremini or white button mushrooms: I prefer cremini for their deeper, almost meaty flavor, but regular button mushrooms work beautifully too and are usually cheaper.
- Shallot: A small shallot brings a gentle sweetness that onion can't quite match, though a quarter of a yellow onion works in a pinch.
- Garlic: One clove is plenty since it can overpower the mushrooms if you go overboard, and I learned that the hard way.
- Swiss cheese: The nutty, mild flavor melts into creamy pools and doesn't fight with the mushrooms like sharper cheeses can.
- Unsalted butter: Softened butter spreads easier and gives you control over the salt, plus a little extra in the pan for the mushrooms makes all the difference.
- Rye bread: The caraway seeds and tangy flavor add character, but if you're not a rye fan, sourdough is a solid substitute.
- Olive oil: A tablespoon keeps the mushrooms from sticking and adds a fruity note that butter alone doesn't give.
- Salt and black pepper: Season the mushrooms well, they need it to bring out their earthy sweetness.
- Fresh thyme: Optional but worth it for the herby brightness that ties everything together.
Instructions
- Start the mushrooms:
- Heat the olive oil and a tablespoon of butter in a skillet over medium heat until it shimmers and smells nutty. Add the shallot and let it soften for about a minute, stirring so it doesn't brown too fast.
- Cook the mushrooms:
- Toss in the sliced mushrooms and spread them out so they have room to breathe. Stir every minute or so for 5 to 7 minutes until they're golden and all the moisture has cooked off, then add the garlic and thyme and cook for another minute until fragrant.
- Season and set aside:
- Taste the mushrooms and add salt and black pepper to your liking, then scrape everything into a bowl and set it aside. The pan should look fairly clean, which makes the next step easier.
- Build the sandwiches:
- Lay out your rye slices and place a slice of Swiss on two of them, then divide the mushroom mixture evenly over the cheese. Top with another slice of Swiss and close with the remaining bread.
- Butter the outside:
- Spread softened butter generously on the outer faces of each sandwich, getting all the way to the edges. This is what gives you that golden, crispy crust.
- Grill until golden:
- Wipe out the skillet, return it to medium-low heat, and lay the sandwiches in carefully. Cook for 3 to 4 minutes per side, pressing gently with a spatula, until the bread is deeply golden and the cheese has melted into gooey perfection.
- Slice and serve:
- Let the sandwiches rest for a minute so the cheese sets just slightly, then slice them in half and serve while still warm. The first bite should be crispy, creamy, and deeply savory all at once.
Save One evening I made these for dinner instead of lunch, served them with a simple green salad, and my partner looked at me like I'd just invented something revolutionary. We ate them on the couch with a bottle of white wine, and it felt like the kind of easy, cozy meal that makes you remember why you love cooking in the first place. Sometimes the best dishes are the ones that don't ask for much but give you everything.
Serving Suggestions
This sandwich is perfect with a bowl of tomato soup for dipping, which feels like the ultimate nostalgic pairing. A crisp white wine like Sauvignon Blanc or even a light lager cuts through the richness beautifully. I've also served it alongside a handful of pickles and potato chips when I wanted something more casual, and it never disappoints.
Customization Ideas
If you want a little kick, spread a thin layer of Dijon mustard on the inside of the bread before you build the sandwich, it adds a sharp brightness that wakes everything up. Gruyère or Emmental are excellent stand-ins for Swiss if you want a slightly different flavor. I've even added a handful of baby spinach on top of the mushrooms when I'm feeling virtuous, and it wilts right into the cheese without making things soggy.
Storage and Reheating
Honestly, this sandwich is best fresh off the skillet, but if you have leftovers, wrap them in foil and reheat in a 350°F oven for about 10 minutes to bring back some of that crispness. The microwave will make the bread sad and chewy, so avoid it if you can. You can sauté the mushrooms a day ahead and keep them in the fridge, which makes assembly even faster when you're ready to cook.
- Store cooked mushrooms in an airtight container in the fridge for up to three days.
- Assemble and grill sandwiches fresh for the best texture and flavor.
- Reheat assembled sandwiches in the oven, not the microwave, to keep the bread crispy.
Save This sandwich has a way of turning an ordinary afternoon into something worth savoring, and I hope it does the same for you. Make it your own, enjoy every bite, and don't be surprised if it becomes your new favorite way to use up mushrooms.
Recipe FAQ
- → Can I use different types of mushrooms?
Yes, cremini, white button, shiitake, or oyster mushrooms all work beautifully. Adjust cooking time based on mushroom size—larger varieties may need an extra 2-3 minutes to release moisture and brown properly.
- → What bread alternatives work best?
Sourdough, whole wheat, or brioche are excellent substitutes. Avoid very thin bread that may tear during assembly. The bread should be sturdy enough to hold the filling without becoming soggy.
- → How do I prevent soggy bread?
Make sure to cook the mushrooms until all liquid evaporates, which concentrates their flavors and prevents moisture transfer. Butter the bread generously on the outside and cook over medium-low heat so the cheese melts before the bread burns.
- → Can I make this ahead of time?
Prepare the mushroom filling up to 2 hours ahead and store in an airtight container. Assemble and cook the sandwiches fresh for best results, as the bread loses its crispness if assembled too early.
- → What cheese pairs well with these mushrooms?
Swiss cheese is traditional, but Gruyère, Emmental, or even aged Cheddar complement the earthy mushrooms beautifully. Avoid soft cheeses that may leak during cooking.
- → How should I serve this sandwich?
Serve immediately while warm and cheese is melted. Pair with tomato soup, a light salad, or crisp white wine like Sauvignon Blanc. Cut diagonally for an appealing presentation.