For the dough: Place the flour, sugar, salt, yeast and spices into a large bowl and mix together with a silicone spatula until combined. Then make a well in the centre and pour in the milk and beaten eggs. Mix with the spatula until a rough dough forms. Then, flour your work surface and removing the dough from the bowl, knead for 5 minutes until the dough has a smooth skin. Then leave to rest for five minutes.
Meanwhile, place the sultanas in a small heat-proof bowl and cover with boiling water. Then set aside.
Add the butter to the dough, one tablespoon at a time, kneading as you go so the butter is completely combined. You will need to re-flour your work surface a few times throughout, as the dough will be very sticky. (If you have a dough scraper, this will also help to manoeuvre the dough.) This process should take around 10-15 minutes.
Once all the butter has been combined, continue kneading the dough for a further 10 minutes until the dough is smooth and pliable and no longer sticky.
Drain the sultanas thoroughly, then mix in the mixed peel and orange zest. Then flatten the dough slightly and scatter over the fruit. Knead the dough together a little to combine the fruit well - the dough will be slightly wet. Lightly oil a large bowl, place the dough inside and cover with clingfilm. Leave this to prove for at least an hour in a warm place, until the dough has doubled in size.
Tip your proved dough out onto a lightly floured work surface and knock back slightly to release the air. Then divide into 12 equal pieces and roll into balls. Place the balls onto a lined baking tray with a little room to grow. Then leave to prove for 45 minutes in a warm place, until puffed up. Meanwhile pre-heat the oven to 220C/200C Fan/Gas Mark 7.
For the crosses: While the buns are proving, make the paste by combining the flour and water in a small bowl until well combined. Then place into a piping bag and cut off the end to create a medium hole. Once the buns have proved, pipe vertical and horizontal lines across each bun. Then bake for 20 minutes until golden brown.
For the glaze: Once the buns are almost finished baking, combine the boiling water and sugar in a small bowl. Take the buns out of the oven, then using a pastry brush, brush the glaze over while still hot. Then leave to cool on a cooling rack.