Melt butter and sugar in saucepan. Remove from heat and mix through the condensed milk then milk. Mix into flour and yeast then knead until silky smooth and rebounds well. Break of smallish chunks of dough and roll into cylinders. Stand them up, nice and close together in a large baking dish. Cover with a damp tea towel and sit somewhere warm for half an hour. Pop in a 180 deg cel oven until centre buns are cooked through. Separate buns and either sit on oven racks on very cool oven until dried through or pop in a food dehydrator. Store in an airtight container in the pantry.