Preheat oven to 400 degrees
Brush French bread rounds lightly with olive oil. Place on baking sheet. Bake for 10 minutes or until rounds are just starting to brown (watch carefully- rounds shouldn't be allowed to brown to golden- they will end up becoming too brittle). Remove from baking sheet.
Heat the 1 Tablespoon olive oil in a pan that has a cover. When the oil is hot, add the mushrooms, salt and sherry. Cover, and lower heat. Cook until liquid is released from the mushrooms, about 10 minutes. Drain and set aside.
Preheat oven to 350 degrees
Wrap garlic cloves, brushed lightly with olive oil, in foil. Bake for 30 minutes, or until soft.
Mash roasted garlic and add to the mayonnaise. Add lemon juice and stir until blended.
Spread toast rounds liberally with alioli and top with mushroom slices. Sprinkle with parmesan cheese.
Broil for about 30 seconds or until alioli just starts to bubble.