To a small saucepan add the milk with a pinch of saffron and warm up lightly without bringing it to a boil. Alternatively, you can warm up the milk in a microwave. In the bowl of a stand mixer, fitted with a paddle attachment, combine the infused milk with the yeast, 50g/¼ cup of the sugar and 100g/3/4 cup of the flour, cover it with plastic wrap and let it rise in a warm place for 1 hour.
With an electric mixer whip the softened butter with the remaining sugar until creamy, then add the eggs, egg yolks, vanilla and the salt. Then add this mixture to the yeast mixture and mix until well combined.
Replace the paddle attachment with a dough hook, add the remaining 400g/3 ¾ cups flour and start kneading until you get elastic dough. This will take 10-15 minutes on medium speed. Towards the end of the kneading time turn the speed up to high and knead for 5 minutes to develop gluten in the dough. At the end the dough will be very soft and a little sticky. Fold in chocolate chips until evenly distributed.
Transfer the dough to an oiled bowl, cover with plastic wrap and let it rise in a warm place for 2 hours-2.5 hours until it’s doubled in bulk. It might take longer if your house is cool.
Divide the dough and with oiled hands transfer into two 5 inch or 6 inch pans. Ideally you pans should also be tall or you can use panettone moulds. You can build up the sides of your pan with parchment paper if your pans are not tall enough. Your dough should come up no higher than halfway up the sides of the pans. Let the dough rise one more time for 40 minutes to 1 hour.
Bake in the preheated to 180C/350F for 35-40 minutes. Take out of the oven and let it cool, then remove from pans when cool enough to handle. Don't remove if using paper moulds.
Cool and glaze with melted white chocolate and decorate sprinkles. The bread is best on the day it is baked or the following day.
Notes
This recipe makes 2 X 5 inch round loaves. This bread could be toasted or made into French toast if you have leftovers and it has gone a little stale.