Make the dough: Mix together all of the dough ingredients on medium in a stand mix for about 8-10 minutes until an elastic dough has formed.

Remove the ball of dough from the mixer, oil the bowl, and then place dough back in and allow to rise until doubled in size (1-2 hours).

While the dough rises, heat a medium size pan on the stove. Add the butter and onions with pinches of salt, pepper, and sugar and saute the onions for at least 15 minutes, up to 30 minutes until they are golden brown but not burnt. Stir often. You are not looking to caramelize the onions, simply saute until most of the water is removed. Allow to cool completely.

Once the dough has risen, prepare a loaf pan with a light coat of butter or other grease.

Assemble the babka by flouring a flat surface lightly then rolling the dough into a large rectangle a few inches larger than the tin on both sides. Cover the dough evenly with the onions and then roll up like a jelly roll from the longer of the two sides.

With a knife cut the roll lengthwise into two long, separate strips then twist the two strips together (you will lose some onions, this is fine). Transfer to the loaf pan with the cut side facing up, cover with a damp towel, and set aside to rise for 30-45 minutes while you preheat the oven to 175°C.

Once the loaf has risen again, bake for 40 minutes or until a toothpick comes out clean when inserted. Allow to cool before cutting and serving.