In the bowl of a stand mixer, add the yeast, 1 Tablespoon sugar and lukewarm milk into a mixing bowl. Stand for 10 minutes until yeast has bubbled and frothed up.
Add the eggs, oil, sweet potato and sugar and mix until well combined.
In the meantime sift together the flour, salt and spices.
Using the dough hook attachment, add in the flour mix one cup at a time until a soft dough forms. Knead for 5 minutes and then add the cake mixture and citrus peel and knead for a further 3 minutes. Dough will be soft and slightly sticky
Turn onto a lightly floured surface to bring everything together with your hands. (This is a step I like to include)
Oil a large bowl and transfer the dough to the bowl. Cover with a tea towel / clingwrap and place in a warm spot. Allow the dough to rise for 1 hour or until doubled in size.
Turn the dough out onto a lightly floured surface. Divide the dough into 15 even pieces (average 110 grams per piece - I usually weigh each lump of dough to ensure they are the same size and an even bake)
Roll each piece of dough into a smooth ball.
Arrange the buns on one or two baking trays lined with parchment, leaving a little space for the dough to expand. Allow to rise for a further 45 minutes or until doubled in size.
Heat oven to 190℃
Mix the flour, sugar and water together until a thick paste forms. Allow to stand for 5 minutes.
Spoon into a ziplock bag and cut off the tip.
Pipe a line along each row of buns and repeat in the opposite direction to create crosses.
Bake for 15 - 18 minutes or until lightly golden brown.
While the buns are baking prepare the glaze by heating the castor sugar and water in a small saucepan. Bring to a boil and simmer for 2 minutes.
Brush the glaze over the top of the warm buns and leave to cool
Store buns in an airtight container and enjoy!