And writing this as I go.
I chopped five challah hamburger buns (I know, what a thing, but they were marked down,) and divided them; there were maybe six cups challah bread total. I don't know. I mixed each half with a couple tablespoons of melted butter and put them in 9 inch cake pans. So, as much as will fit in two of those. Whichever of these you try, just double everything for a 9x13 pan.
To one I added a generous amount (@2 tsp) of cinnamon and half a cup of brown sugar, and to the other, about a half cup of sliced almonds and a half cup of white sugar.
Over each of them I poured two eggs and an egg yolk, whisked, and milk added to that to make two full cups of liquid. The brown sugar one got a splash (let's say 2 tsp) of vanilla extract, and the white sugar one got almond extract. I am going to use the extra egg whites along with their shells to clarify some soup stock which is reducing on the stove.
I forgot to add a little salt, but I think the salted butter will help with that. Also, and this is before I am tasting it, a half cup of sugar might be too much; it looked like a lot as I was sprinking it on, and might want only a third.
They are in the oven at 350º for 35 minutes, and I am expecting them to need at least five more.
Before I finish, I want to point out that the longer the bread cubes soak in the liquid, the more puddingy they will be. Personally, I like them only half-puddingy, suspended in the custard around them, and with a tiny bit of crunch on top, so I don’t let it soak long before baking. That sounds super gross, doesn’t it? But it is delicious. I just adore bread pudding, as long as it doesn’t have raisins in it. It can have chocolate chips in it, if you like to do that*. I don't, but it occurs to me you could add some shaved chocolate and grated orange peel, and that might be really nice. Maybe with a splash of orange liqueur.
Also, sometimes people make a hard sauce to go over it. I do like that, however, as I need to reduce and have no business eating bread pudding in the first place, I’m going to skip it.
*I wish I could remember the name of the book in which an old lady is staying with some kids and they make chocolate chip stale bread pudding. The concept utterly fascinated me, but my mother refused to make bread pudding. Sigh.
In the end, these small pans baked for 39 minutes. The brown sugar one puffed up more, but settled down to the same level as the other.
When you get bread pudding at a restaurant, it's much more dense, because they use a deeper pan, pack in the bread, and also start the custard process before pouring it over the bread cubes, by warming the milk and other ingredients first. I like my way better, and it's simpler to do. And so far, I like both versions, though I might favor the almond one slightly more, because I really love almond-flavored desserts. I'm going to taste them both again later to see if I feel the same way. They would be divine with a little cream poured over the top, or with ice cream, if you really like ice cream. The brown sugar cinnamon one would be good with a chopped apple added to it; if you use a green apple, maybe toss the pieces with a spoonful or two of sugar first, and a squinch of lemon juice. The half cup of sugar was just right otherwise, for a lightly sweet dessert.