In a bowl put the flour, yeast, salt and sugar and mix.
Add the egg mix to the flour and mix. This you can also do on a stand mixer using the hook attachment.
From the moment all the butter is in the dough you'll need to knead for about 10 more minutes or until the dough changes: it will unstick from the table or bowl and go really shiny.
Place the buns we're making one by one into the mould, alternating sides and sightly pressing them back so they can all fit.
Let it proof for 2 hours in a not-so-warm place or an hour in a warm place. The second option is best. I set my oven to 40C but if you can't look for a warm place in your house so the yeast can wake up.
*for any of the other types of yeast you want to first mix them with the milk that needs to be warm and let it activate for 10min.