In a large greased baking dish, place bread cubes. In a large bowl, whisk together eggs, milk, brown sugar and ground cinnamon. Pour the egg mixture over the bread cubes.
Cover and refrigerate overnight. Preheat oven to 350 F. For the topping, in a small bowl, cut flour, brown sugar and cinnamon into butter until crumbly. Sprinkle over the french toast. Bake for 50-55 minutes.