Add the yeast, sugar, water in a small bowl and mix well and leave aside for 10 mins until it froths
Place flour, salt, butter and egg, milk powder mix well using a rubber spatula or spoon
Once the yeast has froth, then add the yeast mixture into the flour and mix it with a rubber spatula until fully incorporated
Add oil to the work surface and transfer the dough on to the surface and knead for about 10-15 minutes. Add raisins at the end at mix for further 1 minute ( If you have a stand mixer with the dough hook, then use the dough hook which will help to knead the dough easily)
Brush a bowl with melted butter and place the kneaded dough inside, cover with a cling wrap and let it rest and double in size in a warm area. ( Note: it may take longer than a usual dough as it is a very sticky and has a high moisture content. The resting time will depend on the humidity and temperature
Once doubled in size knock the air out by punching the dough and cut it into 6 equal pieces
Using your palm in a circular motion, make smooth balls by pressing it downwards and rotating it in one place
Place them on a tray leaving sufficient gaps in between and cover. Let it rise for the second time in a warm area until doubled in size ( you don't need to leave it for a long time, this will take half the amount of time it took for the first rise )
Preheat your oven to 200 Degrees (conventional)
Once the dough has risen egg wash the top just before putting it in the oven
Bake for 12-15 minutes in the middle rack of the oven until the top has a beautiful golden brown colour
Once it comes out of the oven, to get the signature crack top of a Sri Lankan tea bun, close the buns with a clean tea towel for 1 hour.
Enjoy it with a cup of Ceylon tea