Slice pumpkin bread in ¼-inch thick slices. and lay in the bottom of a 8-inch x 11-inch x 2-inch casserole. Set aside.
Slice each piece in half and lay in the bottom of a 8-inch x 11-inch x 2-inch casserole. Set aside.
In a medium saucepan, combine pumpkin purée, sugar, cornstarch, pumpkin pie spice, and milk.
Cook and stir over medium heat until thickened, about 12-14 minutes.
Remove from heat and stir in vanilla.
Pour half the hot custard over the sliced pumpkin bread.
Add another layer of pumpkin bread.
Top with the remaining custard.
When cool, cover with plastic wrap, making sure the plastic wrap is touching the top of the custard.
Refrigerate for at least 8 hours or overnight.