Melt butter in microwave, add brown sugar and mix well, pour in bottom of 9x13 baking dish.
Beat eggs, add milk, vanilla and cinnamon.
Put first layer of bread in the baking dish, on top of brown sugar/butter mixture, to fill any open spaces, I tear bread and stuff into the openings. Spoon egg mixture over each piece of bread, making sure to cover entire piece.
Do another layer of bread, spoon egg mixture over each piece again. Usually, 2 layers is all you'll have room for. Distribute remaining egg mixture over the bread.
This can be cooked immediately, but tastes best if allowed to sit for at least 30 minutes to let the bread soak in the egg mixture.
I usually make this night before and put it in the refrigerator overnight. If you do this, make sure to cover it, and let it set out for about 15 minutes before putting in the oven.
Bake covered at 350 degrees for 30 minutes. Remove cover (aluminum foil), and bake for an additional 15 minutes. May be served with syrup, or the brown sugar/butter layer on the bottom makes it's own syrup.
This can be made without any sugar, and still tastes divine. Just leave out the brown sugar and use only the melted butter in the bottom of the dish.