Coat a 9-by-12 1/2-inch rimmed baking sheet or 6 small loaf pans (2 1/2-by-5-inches) with cooking spray, and line with parchment, leaving an overhang on long sides. Pour melted chocolate into baking sheet or divide among pans (3 tablespoons each), and spread in an even layer. Sprinkle toppings over chocolate. Refrigerate until firm, at least 1 hour. Peel off parchment, and break bark into pieces.