Savory Mushroom & Cheese Grilled Melt

Heat butter and olive oil in a skillet over medium heat.
Add the mushrooms and onions, cooking for 5-7 minutes until softened and caramelized.
Stir in garlic, thyme, salt, and pepper, and cook for another minute. Remove from heat.
Step 2: Assemble the Sandwiches
Spread mayonnaise on one side of each slice of sourdough bread.
On the unspread side, layer shredded Gruyère, the mushroom mixture, and shredded mozzarella. Top with another slice of bread.
Step 3: Grill the Sandwiches
Heat a skillet over medium-low heat. Grill the sandwiches for 3-4 minutes per side, until golden brown and the cheese has melted.
Step 4: Serve
Slice the sandwiches and serve hot!
Serving and Storage Tips