Begin by putting the 225g flour, sugar, spices and zest in the bowl of a stand mixer. Add the water, treacle and yeast and mix everything using a spatula and spoon until completely combined, the mixture will be very wet, don't worry. Cover the bowl and leave to rest somewhere warm for an hour.
After an hour, add the rest of the flour, egg yolks, salt and softened butter to the bowl. With the dough hook attachment on the stand mixer, mix until the dough comes together and all of the butter is mixed in.
Add the mixed peel, sultanas, raisins, stem ginger and ginger syrup to the dough and mix on a medium speed until the dough comes together. It will be quite sticky, but should come away from the sides a bit. Knead for around 5 minutes, until the dough is smooth and glossy.
Cover the bowl of dough and put it somewhere warm to rest for 2 hours.
After an hour, take the dough and shape it into 12 balls dough weighing around 130g per ball. Shape them into rounds and place them on a large baking tray, evenly spaced apart so they have some room to prove. Place the buns somewhere warm to prove covered in a layer of clingfilm. Leave to prove for an hour or until doubled in size.
While the buns are proving, make the flour paste for the cross, sift the flour into a bowl, add a pinch of salt and sugar and then add the water. Whisk together to form a paste and remove any lumps. Place in a piping bag and put to one side for later.
Next make the glaze, put the water, sugar and liquid glucose in a saucepan and bring them to a boil. Keep boiling until it reaches 105c, then put to one side and allow to cool.
Pre-heat the oven to 180C/160C Fan and when the buns are ready, pipe a cross on top and place them in the oven. Bake for 15-20 mins until golden.Remove from the oven and glaze immediately, leave to cool.
These freeze well when baked, just allow to cool completely and then freeze.