01 - Line a small loaf pan or chocolate mold with parchment paper or lightly grease it.
02 - In a heatproof bowl, combine dark chocolate and butter. Melt gently over simmering water using a double boiler, stirring until smooth.
03 - Remove from heat and stir in powdered sugar and vanilla extract until fully blended.
04 - Fold in chopped nuts, dried fruit, and a pinch of sea salt if using.
05 - Transfer the mixture into the prepared mold and smooth the top with a spatula.
06 - Gently tap the mold on the countertop to release any trapped air bubbles.
07 - Refrigerate for at least 40 minutes or until fully firm.
08 - Remove from mold, slice into 8 bars, and store airtight in a cool place.