Spread 8 graham cracker halves with marshmallow spread and set aside. Put chocolate in microwave-safe bowl and microwave on high for about 90 seconds, stirring every 30 seconds, until melted and smooth. With an offset spatula or knife, spread melted chocolate on remaining 8 graham cracker halves. Let cool slightly.
Spoon 1/4 cup rocky road ice cream onto each marshmallow-topped cracker. Top with chocolate-covered graham, chocolate side down, pressing gently. Serve immediately, or wrap in plastic and return to freezer. Sandwiches will keep, frozen, for 2 days.