1. For the dough, measure the flour, sugar, yeast and salt in the bowl of a stand mixer fitted with the hook attachment. Stir the hot water and milk together (the hot water and cold milk should result in a liquid of about 115°F/46°C). Add the milk mixture and the eggs to the bowl and start the mixer on low, letting it go for a minute or two until the dough is almost combined. Add the butter, a few pieces at a time, while the mixer is on. Increase the speed one level and continue to mix until the dough looks smooth (it will be very soft), about 6 minutes.
2. Transfer the dough to an ungreased bowl, cover with plastic wrap and let sit on the counter for an hour. Refrigerate overnight (6 to 24 hours) so the dough firms up.