Preheat a fan-forced oven to 160°C. Line two trays with baking paper.
Melt butter, sugar, and golden syrup in a medium saucepan over medium heat, stirring until sugar dissolves. Add double cream and bring to a gentle simmer, cooking 2-3 mins until thickened.
Stir in orange zest, cinnamon, and cardamom. Add pistachios, cranberries, candied peel, almonds, coconut, and cornflakes, and mix well.
Drop spoonfuls onto trays, spaced about 3-4 cm apart. Flatten each slightly. Bake for 8-10 mins, until edges are golden. Cool 5 mins on the tray, then transfer to a wire rack.
Melt dark chocolate in a heatproof bowl over simmering water. Dip the base of each Florentine, letting excess drip off. Place on wire rack to set.
Let the chocolate set fully at room temp, or chill in the fridge for 10 mins (note: chocolate may lose its gloss if chilled).
