Beat eggs, sugar, milk, vanilla, cream of tartar and spices together.
Grease a large casserole pan
Layer the bread cubes and meat in the pan.
Pour the egg mixture over.
Drizzle the butter over.
Refrigerate for 12 to 24 hours.
Remove from the fridge and allow to come to room temperature for 1 to 2 hours.
Cover with foil and bake 40 minutes.
Remove foil and bake 20 minutes or until golden.
When done, let it rest on the counter for 15 minutes before cutting.
Sprinkle with cinnamon sugar.
Enjoy!