Around 6pm the evening before baking the bread, make the dough.
Combine the milk and butter in a saucepan and heat just until the butter melts. Remove from the heat and add the lemon zest, raisins and currants. Set aside to cool for 10 minutes and plump up the dried fruit.
Combine the flour, sugar, spices and salt in a large mixing bowl. Pour over the warm milk mixture and bubbly sourdough starter. Use a tablespoon to mix together into a shaggy dough. Cover with a plate and leave to hydrate for 30 minutes.
After this time, use your hands to knead the dough directly in the bowl for 2 minutes until smooth, then form into a ball and cover with a plate. Leave to rise in a WARM place for 3-4 hours until it rises by about 30%, then put the bowl into the fridge overnight.
The next morning, around 7-8am, remove the dough from the fridge, tip onto the bench and knead lightly for 20 seconds (if the dough is difficult to handle while cold leave for 30 minutes on the bench to soften). Use a dough scraper or butter knife to divide into four even pieces, then cut each piece into four again. You will now have 16 pieces in total. Roll each into a ball by cupping your hand over the dough and moving in a circular motion.
Grease a 24cm-wide round ovenproof dish (I used a cast iron pan), or a similar sized cake tin. Snugly arrange the dough balls into the dish starting with one in the middle, five placed around this and then ten around the outside. See the photo above for placement as this will be important when it comes to piping on the crosses. Cover the pan/tin with a plastic bag so the dough doesn't dry out and leave to rise in a WARM place for about 2-3 hours until risen by about 30% (see pro tip above).
Preheat the oven to 220°C (fan 200°C).
Prepare the cross paste by combining the flour and water in a bowl and then spoon this into a small ziplock bag. Use scissors to snip off a corner about 3mm wide. Squeeze the flour mix onto the risen dough to make crosses (see the image above for the pattern). Place in the oven and bake for 22-25 minutes until golden.
Remove the bread from the oven. Make the glaze by combining the apricot jam and boiling water together in a small bowl. Use a pastry brush to evenly brush over the hot bread. Cool a little in the pan/tin, then move the bread to a cooling rack. Serve warm with butter and jam.
Notes
*Yeast Variation - If you don't have a sourdough dough starter on the go you can also use yeast to make this recipe - increase the milk to 375ml (1 1/2 cups) total, and to the dry ingredients add 75g (1/2 cup) extra flour and 1 tsp active or instant dried yeast (but not breadmaker yeast such as Surebake).