In a large bowl, weigh out the flour, sugar, salt, mixed spice and sachet of dried yeast.
Add the milk and eggs to the dry ingredients, and mix together until it forms a rough dough (use this lump to mop up any flour sticking to the side of the bowl). Cover your bowl with a damp tea towel or cling film and rest for about 30 40minutes, or until noticeably changed in size.
Inside the bowl, rub the soft butter into your rested dough and repeatedly fold it over until the butter is completely incorporated. Rest the dough until it has doubled in size, probably around 1 hour or so. Whilst it’s resting, prepare a baking or roasting tray by lining it with non-stick greaseproof (baking) paper.
Once rested, turn the dough out onto a well-floured surface. Flour the top, then begin to roll it out with a rolling pin. You want to roll it out into as big a rectangle as you can – it should be no more than about half a centimetre thick. Keep the bottom loose and sprinkle on more flour if you need to. Try to keep it as rectangular as possible.
Once you’ve got your dough into a massive rectangle, brush it liberally with melted butter then sprinkle the sugar and then fruit over evenly. Roll it up into a long sausage like a Swiss roll, keeping it loose so as it not to force any of the filling out. Finally, cut the sausage into buns about 1-2 inches high and arrange them in your roasting/baking tin.
Rest for a final hour, or for 8-12 hours (overnight) in the fridge. At least 20 minutes before you’re going to bake it, preheat your oven to 220C with a stone or baking tray inside.
Bake in the tin for 20-30 minutes, until dark and shiny on the top. Once the buns are out, leave them to cool for 5-10 minutes whilst you make the icing – just mix together about half your icing sugar with enough water to make it runny. Then, add more and more icing sugar until it comes really quite thick, and falls from your spoon like a ribbon. Drown the buns in this icing, and eat soon after.
For a zesty equivalent that adds a whole new layer of flavour, make the icing as normal, but substitute the water for lemon juice. This adds tang and freshness that cuts right through the earth bun.