Ingredients

• For the Dough:
• 1 1/4 cups All-Purpose Flour
• 1/3 cup granulated sugar
• 1 teaspoon salt
• 1 3/4 teaspoon fast-acting yeast
• 1/8 cup butter, melted
• 1 large egg, beaten to mix
• 2/3 cup lukewarm whole milk (80 degrees F to 90 degrees F)
• 1/2 vanilla pod, split open lengthwise
• For the Filling:
• 1/2 cup unsalted butter
• 4 tablespoons whole milk
• 2 cups walnut halves or pieces
• 1/2 cup white sugar
• 2 tablespoons unsweetened cocoa powder
• 1/2 vanilla pod, split open lengthwise
• 1 egg yolk
• To Assemble:
• 1 tablespoon butter, melted
• 1 egg white, beaten to mix
• Powdered sugar and water for a thin drizzle, if desired

Instructions

1. For the Dough: Add the flour and the sugar int to the bowl of a free-standing mixer fitted with the dough hook.
2. Add the salt to one side of the bowl, and the yeast to the other.
3. Make a well in the flour
4. Add the butter, egg, and milk.
5. Scrape the vanilla seeds out of the pod and add them to the bowl.
6. Begin mixing at slow speed.
7. When the dough starts to come together, turn up to medium speed and mix for a further 5 – 8 minutes to make a soft, smooth and stretchy dough.
8. Place the dough into a large, lightly oiled mixing bowl and cover with plastic wrap.
9. Leave to rise for about 1 hour until at least double in size. (Rising time will vary)
10. Meanwhile, make the filling.
11. Put the butter and milk in a small pan and heat until the butter has melted; remove from heat.
12. Put the walnuts, sugar and cocoa powder into the bowl of a food processor and add the seeds scraped from the vanilla pod.
13. Process until it reaches a sandy powder.
14. Add the egg yolk, and the milk and butter mixture, and pulse to combine.
15. Set aside at room temperature.
16. Spread a clean bedsheet over your worktop and dust with flour.
17. Butter a 9×5 loaf pan.
18. Turn the risen dough out on to the sheet and, without knocking it back, roll out into a large rectangle about 20 in. x 8 in.
19. Brush the surface with the 1 tablespoon of melted butter.
20. Dust your hands with flour, then ease them, palms down, underneath the dough.
21. Using the tops of your hands, stretch the dough out from the center until it is very thin and see-through. (you should be able to see the sheet faintly)
22. The rectangle should be just over 3 feet x 2 feet (39 x 24)
23. If the filling has been standing for a long time and seems too thick to spread easily, add a little warm milk to loosen it up a bit.
24. Spread the filling gently over the dough – take care as the thin dough could tear – until evenly covered.
25. Starting at one long edge of the dough, lift the sheet and gently roll the dough up tightly, like a Swiss Roll.
26. Carefully lift the rolled dough and place one end in the bottom corner of the prepared loaf tin. Ease the roll around the base of the tin to form a U shape, then continue laying the roll over the first U shape to form a second U shape on top.
27. Put the loaf tin inside a clean plastic bag, close and leave to prove for 1 hour. Towards the end of the proving time, heat your over to 350 degrees F.
28. Remove the tin from the bag and brush the dough with the beaten egg white. (try and avoid it collecting where the bread meets the pan, to avoid sticking)
29. Bake in the preheated oven for 15 minutes, then reduce the oven temperature to 300 degrees F and bake for another 45 minutes – if the top starts to burn, cover with foil.
30. Remove from the oven and leave to cool in the tin for 30 minutes before turning out on to a wire rack to cool completely.
31. When the loaf is cold, (if desired) mix some powdered sugar with a few drops of cold water to make a runny icing and drizzle it over the top.

Notes