Place the mushrooms lip side up on a baking dish. Top with garlic, parsley and a drizzle with olive oil. Grill mushrooms for about 6 minutes or until tender.
In a food processor, blend the cannellini beans and the olive oil until smooth.
Spread mayonnaise on the top half of the rolls, then evenly divide the bean puree on the bottom half of each roll. Top with arugula, mushroom, tomato and the other half of the roll. Serve immediately.
