Line a 15 x 10 inch sheet pan with parchment paper or Silpat mat. I like to use parchment paper sheets.
In a pyrex bowl set on top of a saucepan with simmering water (about 1 inch water), melt the chocolate. Water should not touch chocolate. Using a rubber spatula, stir occasionally, until chocolate is melted and smooth.
Remove from heat. Stir nuts into chocolate until combined.
Spread the chocolate and nuts mixture into the prepared baking sheet. Spread evenly with an offset spatula to about 1/4 or 1/2 inch thick, depending on how thick you like them, and making sure that everything is evenly distributed. Sprinkle with coarse sea salt.
Cool in refrigerator for 20 minutes, until hardened. Once cooled and hardened, remove from parchment paper and break up into about 20 pieces.