46:25 Dough should not be kneaded with milk because the bread might end up being eaten with meat. If one did make the loaf with milk, it is forbidden even to eat it by itself. This is a preventive measure instituted by the Rabbis in order to prevent it being eaten with meat. If the loaf is small enough that one would eat it at one time (like our challah rolls) or if it was baked in a distinctive shape that would tip one off so one would know not to eat it with meat, it is permitted. The same applies regarding dough kneaded with animal fat. One should not bake a loaf of bread together in the same oven with such things as cheese Danish or meat pies because of the likelihood that butter or fat will run and get under the bread. If this happens, it’s the same as if the loaf was kneaded with meat or dairy ingredients.
46:26 If bread is baked together in the same oven with meat, if the oven is closed and the meat is uncovered, then the bread may not be eaten with milk. However, if the meat is covered or the oven is open – assuming that the oven is large like our ovens – then the loaf is permitted. However, this is only after the fact. One should try not to roast meat in an oven in which bread is baked because of the likelihood that fat will run under the bread. There is reason to be concerned even if the meat is roasting in its own pan.