Save to Pinterest The smell of butter browning in my cast iron skillet always makes me think of rainy Tuesday nights when I'm too tired to plan but too hungry to settle. That's how this sandwich was born. I had half a carton of mushrooms wilting in the crisper, some rye bread from the weekend, and a craving for something warm that didn't require a recipe. What came out of that skillet surprised me so much I made it again the next day.
I made this for my neighbor after she helped me move a bookshelf up three flights of stairs. She took one bite, paused mid-chew, and asked if I'd gone to culinary school. I laughed because I'd burned toast that same morning. But watching her face light up reminded me that good food doesn't have to be complicated, it just has to be made with attention. We ended up eating both sandwiches standing at my kitchen counter, talking until the tea went cold.
Ingredients
- Cremini or white button mushrooms: Cremini have a deeper, earthier flavor, but buttons work perfectly if that's what you have. Slice them evenly so they cook at the same rate, and don't wash them under running water, just wipe them clean with a damp towel to keep them from getting soggy.
- Shallot: Shallots are sweeter and more delicate than onions, melting into the mushrooms without overpowering them. If you only have a yellow onion, use about a quarter of it and chop it finely.
- Garlic: Fresh garlic added at the end keeps its punch without burning. I learned the hard way that garlic goes bitter if you cook it too long with the mushrooms.
- Swiss cheese: The nutty, slightly sweet flavor of Swiss is what makes this sandwich sing. It melts beautifully and has those lovely eyes that make each bite a little different.
- Unsalted butter: Softened butter spreads easier on the bread and gives you control over the salt. I keep a stick on the counter in a covered dish just for moments like this.
- Rye bread: The caraway seeds in rye add a whisper of spice that plays well with mushrooms. Make sure your slices aren't too thin or they'll get soggy under the weight of the filling.
- Olive oil: A little fat helps the mushrooms brown instead of steam. I use regular olive oil here, not the fancy stuff, since the heat would dull it anyway.
- Fresh thyme: Optional, but if you have it, the woodsy note ties everything together. Dried thyme works too, just use half as much.
Instructions
- Start the mushroom magic:
- Heat the olive oil and a tablespoon of butter in your skillet over medium heat until the butter stops foaming. Add the shallot and let it soften for about a minute, stirring so it doesn't brown too fast.
- Cook down the mushrooms:
- Toss in the sliced mushrooms and spread them out in an even layer. Let them sit undisturbed for a minute or two to get some color, then stir and cook for 5 to 7 minutes until they're golden and all the moisture has cooked off. Add the garlic and thyme in the last minute, letting the fragrance bloom, then season with salt and pepper and take the pan off the heat.
- Build your sandwiches:
- Lay out all four slices of rye bread on your counter. Put a slice of Swiss on two of them, spoon the warm mushroom mixture evenly over the cheese, then top with another slice of Swiss and close each sandwich with the remaining bread.
- Butter the outside:
- Spread softened butter generously on the outer sides of each sandwich, reaching all the way to the edges. This is what gives you that golden, crispy crust.
- Grill low and slow:
- Wipe out your skillet, return it to medium low heat, and lay the sandwiches in carefully. Cook for 3 to 4 minutes on each side, pressing gently with your spatula to help the cheese melt and the bread crisp without burning.
- Slice and serve:
- Let the sandwiches rest for a minute so the cheese sets just slightly, then slice them in half and serve while they're still warm and the cheese is gooey.
Save to Pinterest The first time I served this to my brother, he admitted he'd always thought mushrooms were slimy and boring. He ate both halves of his sandwich and then asked if there were more mushrooms in the fridge. It became our unofficial Sunday lunch that winter, made in silence except for the sizzle of butter and the occasional hum of approval. Some recipes don't need words.
Making It Your Own
I've made this sandwich a dozen different ways depending on what's in the fridge. A thin smear of Dijon mustard on the inside of the bread adds a sharp kick that cuts through the richness of the cheese. Gruyère works beautifully if you want something a little more sophisticated, and Emmental is nutty and mild if Swiss feels too strong. Once I added a handful of fresh spinach on top of the mushrooms and it turned into something I'd serve at a dinner party. The bones of this recipe are flexible, so trust your instincts and use what you love.
What to Serve Alongside
This sandwich begs for something bright and acidic to balance the richness. A simple tomato soup is the obvious choice, and it works because it's nostalgic and comforting. But I've also served it with a handful of cornichons and a little dressed arugula, and that felt just as right. If you're pouring wine, reach for a crisp Sauvignon Blanc or a light Pinot Noir. Both have enough acidity to stand up to the cheese without overwhelming the earthy mushrooms.
Storage and Reheating
Grilled cheese is always best fresh, but life happens and sometimes you need to make it ahead. If you must, cook the mushrooms and store them in the fridge for up to two days, then assemble and grill the sandwiches when you're ready. Reheating an already grilled sandwich is tricky because the bread can go from crispy to tough. If you have leftovers, warm them in a dry skillet over low heat, flipping often, or wrap them in foil and reheat in a 300 degree oven for about 10 minutes.
- Store cooked mushrooms in an airtight container in the fridge for up to 3 days.
- Reheat assembled sandwiches gently in a covered skillet to avoid drying out the bread.
- Freezing isn't recommended, the texture of the bread and mushrooms suffers too much.
Save to Pinterest There's something deeply satisfying about pulling a perfect grilled cheese out of a hot skillet, the kind where the cheese stretches as you pull the halves apart and the bread shatters just a little under your teeth. Make this once and it'll become one of those recipes you don't need to look up anymore, the kind you make on instinct when you need something warm and trustworthy.
Recipe FAQs
- → Can I use different mushrooms for this sandwich?
Yes, cremini and button mushrooms work well, but you can also use portobello, shiitake, or oyster mushrooms. Adjust cooking time slightly if using larger varieties, as they may need extra time to release their moisture.
- → What bread alternatives work if I don't have rye?
Sourdough, whole wheat, or regular white bread are excellent substitutes. Brioche or ciabatta add richness, while pumpernickel offers a deeper flavor profile similar to rye.
- → How do I prevent the bread from burning while the cheese melts?
Cook on medium-low heat and avoid high temperatures. Medium-low allows the cheese to melt gradually while the bread toasts evenly. Pressing gently with a spatula helps cheese contact the heat without over-browning.
- → Can I make these ahead of time?
You can prepare the mushroom filling up to 2 days ahead and refrigerate. Assemble and cook the sandwiches fresh for the best texture and melted cheese. Pre-made sandwiches don't reheat as well.
- → What cheese alternatives work for this sandwich?
Gruyère, Emmental, fontina, or Jarlsberg provide similar creamy melting qualities. For a sharper flavor, try aged cheddar or Comté. Avoid fresh cheeses that don't melt well.
- → Is this sandwich suitable for vegetarians?
Yes, it's naturally vegetarian as it contains no meat. Ensure your butter and cheese are vegetarian-certified if you follow strict vegetarian guidelines, as some dairy products may contain animal rennet.