mayonnaise - watch the video to see (for spreading on bread)
cheese - 4 slices (sliced, preferably a melting cheese like cheddar or provolone)
bread - 4 slices (sourdough or other crusty bread)
salt - watch the video to see (to taste)
black pepper - watch the video to see (freshly ground, to taste)
Instructions
Sauté Mushrooms and Scallions: Heat butter in a skillet over medium heat. Add sliced mushrooms and scallions. Cook until mushrooms are browned and tender, about 5-7 minutes. Season with salt and pepper.
Prepare Bread: Spread mayonnaise on one side of each slice of bread.
Assemble Sandwich: Place sautéed mushroom and scallion mixture on two slices of bread (on the mayo side). Top with cheese slices, then cover with the remaining bread slices, mayo side down.
Cook Sandwich: Heat a clean skillet over medium heat. Place sandwiches in the skillet and cook until the bread is golden brown and cheese is melted, about 3-4 minutes per side.
Serve: Remove sandwiches from skillet, slice in half if desired, and serve warm.