Slowly melt 3/4 of the chopped chocolate in 15-30 second increments, stirring after each one, until it is about 70% melted.
Add in a handful of reserved chocolate and stir continuously until it is fully melted and the chocolate is smooth. Keep stirring and adding chocolate, a little at a time until the chocolate is cooled to just barely warm. The more the chocolate is agitated, the better it will set. Test the temper by dipping the back of a spoon and setting it down. If the chocolate sets within about 7 minutes and is shiny and streak-free, it's ready to go. If not, add a little more chocolate and keep stirring until it's ready.
Place a large sheet of wax or parchment paper onto a baking sheet. Pour the chocolate onto the paper, and using an offset spatula or the back of a spoon, spread it out to about 1/4 inch thick.
Working fast because chocolate can set very quickly, gently heat the unwrapped caramels in a measuring cup or small bowl in the microwave, in 15 second increments. Add the heavy cream and stir until the caramel has a smooth and pourable consistency.
Drizzle the caramel onto the chocolate for a marbled effect. Immediately sprinkle the pretzels and peanuts evenly onto the whole thing. Press down gently on the toppings so they adhere well to the chocolate.
Transfer the baking sheet to the refrigerator for about 15 minutes until the chocolate is set.
Move to the freezer for an additional 15 minutes to harden the caramel. This will make it much easier to cut into pieces.
Remove from the freezer and, using a large kitchen knife, cut the bark into jagged, uneven pieces.