Unmold the cranberry sauce from the can, and slice into 1/4-inch-thick rounds. Trim the rounds into 1-inch squares.
Remove the outer rind from the wheel of Brie, leaving the top and bottom rind intact. Cut across into 3/4-inch-thick slices, then cut the slices into 1-inch pieces.
Put Brie squares on mini toasts and top with pieces of cranberry sauce, then wrap in prosciutto and secure with decorative toothpicks. Serve at room temperature.