Bring the milk to the boil, take it off the heat add the butter, stirring until the butter melts. Leave to cool until it reaches hand temperature.
In the bowl of a stand mixer, add the flour, salt, sugar, matcha and yeast, making sure the yeast and salt don't touch.
Pour the warm milk and butter mixture into the centre of the dry ingredients and then add the egg.
Using a dough hook fitted on your stand mixer, mix for about 8 minutes until you have a smooth dough that pulls away from the sides of the bowl and all the flour is mixed in.
Cover the bowl with oiled cling film and leave to rise in a warm place for 1 hr or until doubled in size and a finger pressed into it leaves a dent.
With the dough still in the bowl, tip in the white chocolate, cranberries and cinnamon. Using mixer again, knead the dough, making sure everything is well distributed.
Cover the bowl again with oiled cling film amd leave to rise for another 1 hr more or until doubled in size.
Line two baking trays with baking parchment.
Divide the dough into 14 even pieces (about 75-80g per piece), but you can weigh the whole dough and then divide it by 14 to get a more accurate individual roll weight.
Roll each piece into a smooth ball on a lightly floured work surface. Arrange the buns on one or two baking trays lined with parchment, leaving enough space for the dough to expand.
Cover (but don’t wrap) lightly with more oiled cling film, or a clean tea towel, then set aside to prove for 1 hr more.
Preheat the oven to 200C/180C fan/gas 6.
Mix the flour with about 5 tbsp water to make the paste for the cross – add the water 1 tbsp at a time, so you add just enough for a thick paste. Spoon into a piping bag with a small nozzle. Pipe a line along each row of buns, then repeat in the other direction to create crosses. Bake for 20 mins until golden brown.
Gently heat the apricot jam to melt, then sieve to get rid of any chunks. While the jam is still warm, brush over the top of the warm buns and leave to cool.