Step 1: Prepare Mushrooms

1. Clean the mushrooms by gently wiping them with a damp cloth or rinsing under cold water. Pat dry and slice thinly.
2. In a large skillet over medium heat, melt 1 tablespoon of butter until bubbly.
3. Add sliced mushrooms in a single layer (cook in batches if necessary to avoid overcrowding). Let them cook undisturbed for 4-5 minutes to caramelize.
4. Stir the mushrooms and cook for another 3-4 minutes until golden brown.
5. Add minced garlic, stir, and cook for 1-2 minutes until fragrant. Season with salt and pepper to taste. Remove from heat and set aside.

Step 2: Assemble Sandwiches

1. Spread softened butter on one side of each bread slice.
2. Place the unbuttered side of one slice on a clean surface. Layer half the mushroom mixture evenly over it, followed by half the shredded cheese.
3. Top with another slice of bread, buttered side facing out. Repeat for the second sandwich.

Step 3: Grill the Sandwiches

1. Heat the skillet over medium-low heat. Place sandwiches in the skillet without overcrowding.
2. Cook each side for 3-4 minutes until golden brown, pressing gently with a spatula for even cooking.
3. Flip carefully and cook the other side until the bread is crisp and the cheese is melted.
4. Remove sandwiches from the skillet, slice diagonally if desired, and serve immediately.