If desired, spray slow cooker insert lightly with non-stick cooking spray. Add chopped almond bark, chocolate chips and German chocolate.
Place a clean, dry kitchen towel over the top of the slow cooker, then place lid on top of that. Cook on HIGH for 1 hour. Reduce heat to LOW, and cook 1 more hour (or until fully melted), stirring every 15-20 minutes.
Remove lid and towel (be careful not to let any condensation drip into melted chocolate), and add peanuts, stirring well to combine.
Line several baking sheets with wax paper. Drop candy mixture by spoonfuls onto wax paper (or use small cookie scoop). If using sprinkles, sprinkle onto clusters before they harden.
Refrigerate (if possible) 30 minutes to 1 hour, until set. If unable to refrigerate, let stand on counter at room temperature until set. Store in a cool place in an airtight container.