Start the evening before you want the bread. Measure the flour into a big bowl and make a well in it.
Measure in the yeast and one spoonful of the sugar.
Pour over the water, flick some flour over the top of the water, and let it sit for one hour.
Add the rest of the dough ingredients EXCEPT the butter and knead well for 10 minutes. Then, add the butter and continue to knead for up to 20 minutes. Don't panic. The butter will melt and a lake of dough will form. Keep going! The dough will come together and darken in colour, getting golden streaks. It will be the texture of chewing gum.
Cover with plastic wrap and let it sit out of the fridge for 1-2 hours so it begins to rise. Then, place it in the fridge until the morning.
Make the filling ingredients by melting the butter and chocolate together. Stir in all the other filling ingredients except the pistachios. Cover with plastic and set aside until the morning.
Remove the dough from the fridge, and scrape it out of the bowl onto a lightly floured surface. Divide it in two.
Roll one piece into a rectangle that is about 1.5 times the length of your tin and about 1/2 cm thick.
If your filling has solidified overnight, heat it VERY BRIEFLY just to soften it. You don't want it to be hot or it will kill the yeast.
Spread half the filling over the dough, scatter over half of the pistachios, and roll it up along the long side. Wrap it in plastic wrap and place it in the freezer. Repeat with the other piece of dough.
Generously butter two small bread tins or line them with non stick parchment. You are making two loaves!
After 5-10 minutes, remove the dough from the freezer. Unwrap them and, one at a time, with a sharp knife, cut the rolls of dough in half along the lengths.
Twist two halves these together, trying to keep the cut sides up and on the outside of your twist because they are pretty. Repeat with the other two halves. Pop them in the tins.
Cover and let rest for 2-4 hours. It depends on the heat in the kitchen. They will visibly rise.
Preheat the oven to 375 F/190 C. Glaze the loaves with the egg wash and pop them in. Bake for 35 minutes but check after 20 to make sure they are not going too brown. If they are too brown, cover them with non stick baking parchment.
Remove from the oven and remove from the tin. Let cool on a wire rack.
You can fill these with whatever you want. At Easter it's nice to use Marzipan with chopped almonds and poppy seeds. You can use butter/sugar/cinnamon or cardamom, you can use whatever nuts you like, you can do jam if that's all you have or nutella if you are desperate. Anything that is festive and looks pretty!