Preheat oven to 190C (375F).
Lightly crush the flaked almonds and chop the pistachios. Roughly chop the cranberries. Place in a small bowl along with the freeze dried raspberries.
Melt the butter and sugar together in a heavy-based saucepan - don't take this too far, you don't want browned butter here! Add the flour and stir together to form a kind of roux.
Add the cream and beat with a whisk until you have a smooth consistency.
Stir in the nuts, cranberries, freeze dried raspberries and a big pinch of salt (if liked).
Place teaspoonfuls of the mixture onto lined baking sheets - ideally using a non-stick baking mat. I'd reckon on about 6-8 max per sheet.
Bake for 10-12 minutes until just golden brown. The florentines should have flattened out. Let them cool briefly on the baking sheet before transferring to a cooling rack to cool completely.
Melt the dark chocolate and spoon some over the back of each florentine so that you have a nice thick coating. Finish by sprinkling with more freeze dried raspberries or edible rose petals and leave to set.