Put the chopped chocolate in a heat-proof bowl and set it over a saucepan with barely simmering water and allow it to melt. Be careful not to overheat the chocolate, or it will seize up. Once the chocolate is about 90% melted, take it off the water and stir constantly with a spatula until completely melted and smooth. If there are still a few chunks left, place back over the simmering pot for 30 seconds at a time and stir until it all melts.
Cover a large baking sheet with parchment paper. Use a rubber spatula to spread the melted chocolate evenly over the parchment. It won't cover all of the parchment, so just aim for ~1/4" thick all around. It doesn't need to be exact!
Sprinkle the nuts and seeds over the chocolate, and then the dried fruit. Lastly, sprinkle the flaky salt. Gently press all of the toppings into the chocolate.
While that starts to cool, set up the double boiler again (bowl over simmering pan) but for the white chocolate. Be EXTRA careful not to over-heat white chocolate, it's even more delicate than regular chocolate. Once melted, drizzle the white chocolate over the chocolate and toppings with a spoon, as much or little as you'd like.
You can put the baking sheet in the fridge if you need it to set fast, but it can end up creating "chocolate blooms" on the surface of the chocolate which don't look all that good. If possible, leave out to cool at room temperature for ~2-4 hours.
Once the chocolate has hardened, use your hand to break it apart into ~20 pieces. Serve immediately, or cover with plastic wrap and store at room temp for 1 week.
Enjoy!
