Brioche Crab Melts

Name: Brioche Crab Melts
Ingredients: 8 small, round brioche or buttery dinner rolls, split crosswise; 6 tablespoons truffle butter or unsalted butter, softened (see Note); 1/2 cup mayonnaise; 1/4 cup minced red onion; 1/4 cup chopped flat-leaf parsley; 1 tablespoon fresh lime juice; 1/2 Granny Smith apple—quartered lengthwise, cored and thinly sliced crosswise; Several dashes of hot sauce; Salt and freshly ground pepper; 1 pound lump crabmeat, picked over; 1 1/2 cups shredded Gruyère cheese