Over medium heat in a medium saucepan, heat butter and garlic. Place the snails in the saucepan and slowly cook until tender, about 5 minutes.
Remove and discard mushroom stems. Fill the mushroom caps with 1/2 teaspoon melted butter with garlic from the saucepan. Place under grill for 2 to 3 minutes. Insert the snails in the mushroom caps. Grill another 2 minutes.