Heat the butter in a frying pan, preferably non-stick and saute the onions for about 5 minutes on medium-low heat until they soften and start becoming translucent. You don't want them to brown, but they retain texture. Allow to cool.

You can make this by hand or use a mixer with a paddle attachment. Place all the dry ingredients into a bowl and mix to combine. Add the buttermilk and cooled onions buttermilk and very quickly mix to incorporate. Do not overmix.

Tip out on a floured surface and bring the dough into a round ball. Flatten this slightly and cut 4 slits around the sides - about 1/4 of the way into the dough.

Lift the dough onto a lined baking sheet and bake in an oven that has been preheated to 200C for 35 - 45 minutes. It is done when it is browned on the outside and gives a hollow sound when tapped. You could also test by piercing with a sharp knife.