A few hours ahead, or even a day ahead, soak the cherries in kirsch.
Melt the butter. Sift the flour into a bowl. Heat the milk to lukewarm, pour into a jug and stir in the yeast, sugar and a pinch of sea salt. Leave for 5 minutes, then stir in the butter and beat in the egg. Pour into the flour and mix till smooth and shiny. Turn onto a floured surface and make a hollow in the centre.
Drain away any excess booze from the cherries before adding them. Chop and add the mixed peel and almonds, followed by the cinnamon. Knead well. After about 5 minutes the dough should be elastic, but not sticky.
Flour the bowl and put the dough back. Cover with a cloth and leave for 1 to 2 hours, till doubled in size.
Empty the dough onto a floured surface and briefly knead; roll into a 36cm x 26cm rectangle. Roll the marzipan out to be the same length and place along the middle. Fold the dough over, encasing the marzipan, and place on a tray. Leave to rise until doubled.
Preheat the oven to 190ºC/gas 5.
Bake the stollen for 45 minutes, till golden. Leave to cool on the tray for 5 minutes, then transfer to a wire rack. Sieve the icing sugar into a bowl, add the clementine zest and juice to make a thick icing. Drizzle over the stollen before serving.