01 - Line an 8 x 8 inch baking pan or chocolate bar mold with parchment paper.
02 - Melt the chopped dark chocolate and coconut oil (if using) in a heatproof bowl over simmering water, stirring gently until smooth.
03 - Remove the melted chocolate from heat and fold in the roasted mixed nuts and optional dried cranberries or raisins.
04 - Pour the chocolate mixture into the prepared mold, spreading it evenly with a spatula.
05 - Tap the mold gently to release any trapped air bubbles and sprinkle flaky sea salt atop if desired.
06 - Refrigerate for at least 40 minutes until fully set.
07 - Once firm, remove from the mold and cut into 8 bars or break into pieces.