Golden Onion & Mushroom Melt

 

Sometimes a sandwich is so good that I just can’t wait to dig in, making it tough to snap that perfect blog-worthy shot. Let’s face it, I've got this hot, gooey masterpiece fresh from the skillet, and the urge to eat it is real! So, I’m sorry if these photos don’t quite do it justice because this Golden Onion & Mushroom Melt is pure comfort food bliss, with sweet caramelized onions, savory mushrooms, and melty Swiss cheese nestled between crispy sourdough. The flavors are bold, the prep is simple, and the result is a sandwich that’s worth every bite, camera-ready or not.

Golden Onion & Mushroom Melt 

1 large yellow onion, thinly sliced

1½ T. olive oil, divided

½ t. butter

½ t. brown sugar

¼ t. balsamic vinegar

½ lb. cremini mushrooms, sliced

1 clove garlic, minced

½ T. fresh thyme (or ¼ t. dried thyme)

2 T. dry white wine (NOT optional)

Salt and freshly ground black pepper to taste

2 slices sourdough bread

2 oz. Swiss cheese, thinly sliced

1 T. butter, softened

½ T. Dijon mustard

In a skillet, heat 1 tbsp olive oil and ½ tbsp butter over medium-low heat. Add sliced onion and cook, stirring occasionally, for 20-30 minutes until golden brown. Stir in brown sugar and balsamic vinegar, cook for 2 minutes, then season with salt and pepper. Set aside.

In the same skillet, heat ½ tbsp olive oil over medium-high heat. Add mushrooms and cook for 8-10 minutes until browned. Add garlic, thyme, and white wine (if using), cooking for 1-2 minutes until the wine evaporates. Season with salt and pepper.

 Butter one side of each bread slice.On the unbuttered side of one slice, spread Dijon mustard (if using), then layer with Swiss cheese, caramelized onions, and mushrooms. Top with the second slice, buttered side up.

 In a clean skillet over medium-low heat, cook the sandwich for 3-5 minutes per side until the bread is golden and the cheese is melted. Cover the skillet to help the cheese melt.

 Cut the sandwich in half and enjoy immediately while it’s hot and melty!

The Golden Onion & Mushroom Melt is the ultimate comfort food. The onions, slow-cooked to sweet perfection, pair beautifully with earthy mushrooms and nutty Swiss cheese. Sourdough bread adds a tangy crunch, and a touch of Dijon mustard brings a subtle zing. It’s an easy recipe that feels gourmet, perfect for a cozy lunch or quick dinner. Plus, it’s vegetarian-friendly and endlessly customizable—swap cheeses or add a sprinkle of red pepper flakes for a kick!

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