This is a version of my recipe for naturally leavened Panettone, adapted to use brewer’s yeast instead of a sourdough starter. Unlike that recipe, which requires several days in the making, this one can be made in a day. I would suggest you pick a day when you know you will be around to intervene at the various stages of the bake. I also suggest that you start early. It should only take about 8-10 hours from start to finish, but a numbers of factors could cause this to vary.