01 - Place chopped dark and milk chocolate with unsalted butter in a heatproof bowl. Set over a saucepan of gently simmering water, stirring until completely melted and smooth. Remove from heat and mix in heavy cream. Allow to cool slightly.
02 - Line an 8-inch square pan with parchment paper. Evenly spread the melted chocolate mixture into the pan.
03 - Scatter crushed pistachios, digestive biscuit pieces, and toasted coconut flakes over the chocolate base. Press gently with a spatula to integrate the layer.
04 - Combine pitted Medjool dates, water, ground cardamom, and sea salt in a small saucepan. Cook over low heat while stirring, until the dates soften and liquid mostly evaporates, about 5 minutes. Puree the mixture until smooth with a blender or immersion blender.
05 - Spoon or swirl the date caramel over the layered chocolate base. Refrigerate for at least 2 hours, until completely set.
06 - Remove from pan, slice into bars or squares. Decorate with edible gold leaf, dried rose petals, and additional chopped pistachios just before serving.