Put the flour, sugar, yeast, mixed spice and salt into a large bowl and mix to combine.
Heat the milk in a glass jug until it's warm. Add the melted butter, egg and egg yolk to the glass jug and whisk together.
Pour the milk mixture into the flour mixture and stir to form a sticky dough.
Lightly flour a surface and turn the dough out on to it. Knead for 8-10 minutes until the dough is smooth and stretchy. Alternatively, you can use a stand mixer fitted with the dough hook, mix on a low speed for 8 minutes.
Put the dough into a lightly oiled bowl and cover with oiled cling film. Leave to rise in a warm place for two hours or until the dough has doubled in size.
Meanwhile, add the cranberries, mixed fruit, lemon zest, orange zest and orange juice into a small saucepan. Heat for 5 minutes until the fruit is plump and juicy. Set aside to cool.
When the dough has risen, turn it out onto a lightly floured surface. Roll it into a rectangle measuring approximately 50cm x 30cm.
Scatter the grated marzipan over the dough followed by the soaked fruit and three-quarters of the pistachios. Gently press the filling into the dough using your hands.
With the longest side facing you, roll up the dough into a sausage shape. Pinch the seam to make a seal then cut the dough into two long pieces leaving one end intact.
Plait the dough in a criss-cross pattern then join the ends up, pinching together to form a circle. Slide the Stollen wreath onto a large baking tray lined with baking paper, cover it with oiled cling film and leave to rise in a warm place for 30 minutes.
Preheat the oven to 180ºC/160ºC Fan/Gas 4/350ºF
When the dough has had its second rise, bake it in the centre of the oven for 45 minutes or until it is uniformly golden in colour.
Remove from the oven and immediately brush with 25g melted butter, scatter over the remaining pistachios and generously sprinkle with icing sugar.