1. Sieve the flour and salt into a large bowl. Add the dried yeast and sugar to the warm water and leave to stand for 5 minutes until it starts to react (it will go slightly foamy). If using fast-action yeast stir it directly in to the flour with the sugar. Stir the chilli into the flour.
2. Add the yeast water to the flour (if using fast-action yeast just pour in the warm water) and the melted butter and mix with a wooden spoon until the mixture comes together.
3. Tip it out onto a lightly floured surface and knead for 12-15 minutes by hand (or 5-7 in an electric mixer with dough hook), adding more flour or water if necessary to make a smooth but not sticky dough.
4. Oil a large bowl and place the dough inside, covering the top of the bowl with a piece of oiled cling film. Place in a warm place to rise; it should take about 1 hour.
5. When the dough has risen to double its size, punch your fist into the dough to deflate it and turn it out onto a lightly floured surface and knead for about 1 minute.
6. Divide the dough into 10 pieces and shape each one into a ball. Push a chunk of chocolate into the middle of each and pull and pinch the dough over to encase it inside, keeping a round shape with the seam on the bottom.
7. Place the rolls, seam side down, on a lightly oiled baking sheet and cover with another piece of oiled cling film. Leave to prove (rise again) for another half hour or so. Preheat the oven to 200C / gas mark 6.
8. Mix the icing sugar and cocoa powder together and use a sieve to lightly dust the tops of the rolls. Bake for 20 minutes until risen and golden. Place on a wire rack to cool.