Cream butter and brown sugar with the whisks of the mixer. Stir in the eggs one by one. Mix flour, tartar baking powder, baking powder, gingerbread spice and just 1⁄2 tsp. salt. Stir briefly into the butter-sugar mixture.
Preheat the oven (electric cooker: 175 °C/recirculating air: 150 °C/gas: see manufacturer). Line two baking trays with baking paper. Mix white sugar and cinnamon. Form approx. 45 walnut-sized balls from the dough.
Turn in the cinnamon sugar and spread it on the baking trays at a distance. Bake in a hot oven for 8-10 minutes one after the other until golden brown (the biscuits should still be soft inside!).
Remove and immediately sprinkle with the rest of the cinnamon sugar. Leave to cool on the trays.