Preheat oven to 350° F with rack in middle. Whisk together pumpkin, milk, sugar, eggs, yolk, salt, and spices in a bowl.
Toss bread cubes with butter in another bowl, then add pumpkin mixture and toss to coat. Transfer to an ungreased 8-inch square baking dish and bake until custard is set, about 50 minutes. After 30 minutes, top pudding with foil to prevent burning.
I also sprinkle it with the cinnamon chips about 10 minutes before it comes out. Let it sit for about 10 minutes before serving, and store any leftovers in the fridge.
Also, on a sidenote: the recipe I have for cinnamon sauce goes great with this. :).