Place warm water and first measure of sugar in a small bowl. Stir to dissolve sugar.
Sprinkle yeast over and leave for 10 minutes or until frothy.
Combine 3 cups of the flour and salt in a large bowl. Stir in second measure of sugar. Set the remaining ½ cup flour aside.
Make a well in the centre of dry ingredients. Pour in milk, butter and frothy yeast mixture. Beat with a wooden spoon until mixture forms a ball, adding more flour if necessary.
Turn out onto a lightly floured surface. Knead dough until smooth and elastic. Lightly brush bowl with oil. Place dough in bowl. Lightly brush with oil. Leave in a warm place until doubled in size.
Punch dough down in the centre. Lightly knead then roll dough out to a 30 × 25cm rectangle. Spread dough with filling. Roll up like a sponge roll and using string or a knife, cut into 12 even sized pieces.
Arrange in a greased 25cm sponge sandwich tin, nine around outside edge and three in the centre. Cover and leave in a warm place until double in size.
Bake at 190˚C for 25 minutes or until golden. Brush with glaze while hot.
For the icing drizzle, mix all ingredients well, adding enough milk or water to achieve your desired consistency. Drizzle over warm or cooled buns.