1. Place the milk and butter in a small pan and heat gently so the butter melts and the milk is warm.
2. Drain the cherries form the syrup and heat the syrup in a pan with the caster sugar.
3. Mix the cornflour with a little water to slacken then add to the warm syrup in the pan. Heat until it begins to boil and thickens. Remove from the heat and add the cherries.
4. Place the flour in a large bowl, add the yeast to one side and the sugar and salt to the other. Crack the egg into the middle and gradually add the warm milk and butter (make sure the milk is warm and not hot). Using your hand bring the mixture together until a soft dough is formed.
5. Place on a lightly floured work surface and knead for 5 minutes until you have a smooth dough. Place in a lightly greased bowl, cover and leave to prove until doubled in size, this will take between 1 and 3 hours.
6. Tip the dough onto a lightly floured surface and divided into 6 equal pieces. Place three or four cherries in the middle of each ball and bring the dough up around them and pinch the top to seal.
7. Place the balls onto a work surface with pinched bit now on the bottom. Gently roll into a ball. Place on a tray and leave to prove for 10 minutes.
8. Take a large casserole pan and heat very gently, add the butter so it begins to melt, add the salt and sugar. Take the dumplings and begin by placing one in the centre of the pan then place the remaining ones around the edge leaving space between them to expand.
9. Pour in enough water so there is about 1 cm in the base of the pan. Cover and cook a low to medium heat for 15-20 minutes.
10. After this time remove the lid. If there is still liquid present increase the heat and cook for a further 5 minutes. Be careful not to burn the base, they should be golden on the bottom, set on the top and have doubled in size.
11. While they are cooking make the custard. Split the vanilla pod in half and scrap out the seeds. Place it in a pan with the milk. Heat to just below boiling point.
12. In a bowl, beat the egg yolks, sugar and cornflour until well mixed. Pour the hot milk onto the egg yolk mixture and whisk continuously, return to the pan and on a very low heat simmer until the custard has thickened.
13. Don’t rush this and increase the heat or the custard will split.
14. To serve, remove the dumplings from the pan, dust with icing sugar and pour over the custard. You can serve any remaining cherries on the side.