Line a baking sheet with parchment paper; set aside.
Place the chopped bittersweet chocolate in a medium bowl and microwave at 50% power in 30-second increments, stirring after each, until completely melted and smooth. Pour the chocolate onto the prepared baking sheet and, using an offset spatula, spread into a thin layer (about ¼-inch thick - a 12x10-inch rectangle). Sprinkle the melted chocolate with the chopped Butterfingers, Heath bars, peanut butter cups and honey roasted peanuts, making sure all pieces touch melted chocolate (so they adhere). Lightly press to make sure the candy adheres to the melted chocolate. Refrigerate for 30 minutes.
Melt the white chocolate using the same method as the bittersweet chocolate (in a microwave in intervals) until completely smooth. Using a spoon, drizzle the white chocolate over the chilled bark in a zigzag pattern. Scatter the M&M's (or Reese's Pieces) over the white chocolate drizzle, and again press to make sure the candy adheres to the melted white chocolate. Chill again until the white chocolate is set, about 30 minutes.
Cut/break the bark into irregular pieces and serve. Store leftovers in an airtight container in the refrigerator.