In a saucepan over low heat, melt marshmallows and chocolate chips with milk. Remove from heat; cool. In a skillet, stir coconut in butter until browned. Remove from the heat; stir in crumbs. Pat three-fourths into a 13-in. x 9-in. x 2-in. baking pan; cool. Spoon half of the ice cream onto crust. Top with half of the chocolate mixture. Layer with remaining ice cream and chocolate. Sprinkle with remaining crumbs. Cover and freeze for at least 2 hours.