Grease a 9 x 13 baking dish. Slice prepared banana bread into 1/2-3/4 inch slices. (Optional: trim to make more rectangular.) Lay them in a single layer in the bottom of the baking dish.
Prepare the custard in a 4 cup glass measuring cup or a medium mixing bowl. Add all the ingredients and mix well with a whisk or a fork.
Pour the custard over the bread. Cover and allow the mixture to soak into the bread for 2-3 hours or over night.
Bake in a 350° oven for 35-40 minutes.
Serve with butter and real maple syrup or by itself.
