Heat broiler. Lay cake wedges on sides; cut each crosswise in half and place on a baking sheet. Broil cake until brown on top, 2 to 5 minutes. Pulse candy in a food processor. Microwave chocolate in a bowl, stirring every 15 seconds, until smooth, 1 to 2 minutes. Dip untoasted side of cake in chocolate; place on platter chocolate side up. Sprinkle candy pieces over chocolate.