First, make the pastry. Into a large bowl, weigh the flour. Weigh the butter and chop it into cubes. Rub the cubed butter into the flour using your fingers – take two handfuls of floury butter and use your thumbs to rub up the rest of your fingers like a washboard. You want it like breadcrumbs. Alternatively, use a food processor.
Once together, add 2 tbsp. water and mix together. If it doesn’t come together, add a drizzle more. The most important thing about pastry isn’t not to overmix it – it’s not to add too much water. Add as little as you can get away with. Once it is just about coming together, work it a bit with your hands to bring it into a ball of dough. Wrap in cling film and rest in the fridge for at least 15 minutes.
Whilst it’s resting, preheat the oven to 170C/150C fan/Gas 3. Grease (heavily) and line a 2lb loaf tin with baking paper – cut out a long piece that’s the same width as the loaf tin, so you can lift out your bun when it’s done.
Into another large bowl, weigh out ALL the rest of the ingredients. Basically, all you want to do is mix them together until everything is evenly distributed. Once this is done, it’s time to roll the pastry.
Divide the pastry into two pieces – one about 5x bigger than the other. The latter is for the lid. Roll out the big piece until it is about as thin as a pound coin. Keep it moving all the time and use plenty of flour. Place it gently into your loaf tin, pushing it right in to the corners. Make sure there’s at least 1cm hanging over the edge (patch it with spare if needed).
Place your filling inside, smooth it out then flap your excess pastry over the top of it. Brush this excess with milk. Now, roll out your piece for the lid and place it on top. Press down to seal, then trim around the edge with sharp knife. Finally, brush the top with more milk, cut a hole in the middle and place in the oven for at least 1 hour 30 minutes. It should be a dark golden brown on top and a skewer should come out clean when it’s done. If you’ve got a thermometer, check the centre is at least 80C. Leave to cool for at least one hour – it will last for a good couple of weeks if wrapped up in cling film.
Many of us are very busy at Christmas. No one’s going to know if you take a few shortcuts: if you buy some ready-made (even ready rolled) shortcrust pastry, this recipe because as quick and easy as mixing a load of stuff together and shoving it in the oven.