Butter a 9x13-inch baking dish; arrange slices of bread on the bottom.
Beat eggs, milk, cream, vanilla, and cinnamon together in a large bowl. Pour over bread slices, cover, and refrigerate overnight.
The next morning, preheat the oven to 350 degrees F (175 degrees C). Meanwhile, combine butter, brown sugar, and corn syrup together in a small saucepan; heat until bubbling.
Pour over bread and egg mixture.
Bake in preheated oven, uncovered, for 40 minutes.