5/5 Portabella Mushroom Sandwiches With Roasted Garlic Basil Mayo Recipe. 12April2015 - So delicious! Used about five roasted garlic cloves and an onion ciabatta bun. Toasted bread on grill pan: sharp white cheddar (instead of Parmesan) melted on one half, butter on the other. Also added lettuce and thinly sliced onion.