Whisk together everything except the chocolate chips. The mixture needs to be warm enough to keep the butter from clumping. Add the chocolate chips and mix up.
Grease a 9x13 pan, add bread, then add mixture. Mix with your hands to make sure it's well mixed. Let sit at least 20min, longer for drier bread.
Cook at 325F for 45-70min, until all the egg-milk mixture has firmed up. If it's thinner (like a half recipe in the same 9x13 pan) it takes much less time, more like 25min.