1. Preheat the oven to 170°C, gas mark 3. Grease a 3.5 litre bundt tin (or large ring mould) thoroughly with butter. Place 200g of the dates and 100ml of boiling water in a food processor and blend until smooth. Chop the remaining dates roughly and mix in together with the chopped stem ginger.
2.Place the bicarbonate of soda and flour in a large bowl with the mixed spice and sugar and mix to combine. Add the butter, eggs and date mixture and stir everything together to make a thick batter.
3. Spoon into the prepared tin and bake for 45-50 minutes until firm to the touch and an inserted skewer comes out clean. Leave to cool for 5 minutes then turn out onto a wire rack.
4. Place all the ingredients for the sauce in a saucepan and warm over a low heat until melted and the sugar has dissolved. Increase the heat and simmer for 10 minutes until thickened. Drizzle a little of the warm sauce over the cake, then serve cut into wedges with crème fraîche and extra sauce on the side.