This Caramelized Onion & Truffle Mushroom Melt takes the humble grilled cheese to the next level. Deeply caramelized onions meet earthy mushrooms kissed with truffle oil, all topped with gooey cheese and sandwiched between buttery rye slices. Toasted until golden and crisp, it’s a decadent, soul-warming meal that feels both rustic and refined.
Prep Time 15 minutes mins
Cook Time 25 minutes mins
Total Time 40 minutes mins
Course Breakfast, Snack
Cuisine American
Servings 2
Calories 550 kcal
- 4 slices rye bread
- 1 large onion thinly sliced
- 2 tbsp olive oil
- 1 tsp balsamic vinegar optional, for depth
- 200 g mushrooms e.g., cremini or mixed wild, sliced
- 1 tsp truffle oil or to taste
- Salt and pepper to taste
- 100 g Gruyère cheese grated (or vegan cheese alternative)
- 1 tbsp butter or vegan butter for toasting
Caramelize the Onions: In a skillet over medium-low heat, add 1 tablespoon olive oil and the sliced onions.
Cook slowly for 15–20 minutes, stirring occasionally, until golden and soft.
Add balsamic vinegar in the last few minutes if desired. Set aside.
Sauté the Mushrooms: In another pan, heat 1 tablespoon olive oil over medium heat.
Add mushrooms, season with salt and pepper, and cook until they release moisture and become golden (about 6–8 minutes).
Remove from heat and drizzle with truffle oil.
Assemble the Sandwich: Layer Gruyère (or vegan cheese), caramelized onions, and mushrooms on two slices of rye bread.
Top with the remaining bread slices.
Toast the Melt: In a skillet, melt butter over medium heat.
Toast the sandwiches for 3–4 minutes per side until the bread is golden and the cheese is melted.
Serve: Slice and serve warm, optionally with a side of greens or pickles.
- For extra crunch, add a handful of arugula or baby spinach before closing the sandwich.
- Truffle oil is potent—start with a small amount and add more if desired.
- Pairs beautifully with a glass of red wine or a bowl of tomato soup.
Tip: Make it party-ready by turning it into mini melts using baguette slices and baking in the oven!Keyword caramelized onion sandwich, cozy lunch ideas, gourmet grilled cheese, Gruyère melt, mushroom melt, plant-based sandwich, rye bread sandwich, savory vegetarian, truffle mushroom recipe, vegetarian melt