You can stop there and chill the whole thing overnight and bake it in the morning, or you can get it in the oven straight away. In either case, it will bake in two phases – once to set and once to brown the streusel topping. (Because why wouldn’t you want a buttery, golden brown sugary topping? Exactly.)
1 lb loaf French bread, cubed
8 large eggs
1 1/2 cups whole milk
1 cup heavy cream
1/2 cup granulated sugar
1/4 cup light brown sugar
1 tablespoon vanilla extract
2 teaspoons ground cinnamon
6-7 bananas, 1 sliced, the rest chopped
FOR THE STREUSEL TOPPING:
3/4 cup all-purpose flour
3/4 cup brown sugar
1 teaspoon cinnamon
1/2 cup salted butter, chopped
When ready to bake, preheat oven to 350°F and grease a 9×13-inch baking dish.
In a large bowl, whisk together the eggs, milk, cream, sugars, vanilla extract, and cinnamon.
Add bread and chopped bananas and stir to combine. Pour into prepared baking dish and cover tightly with foil. Refrigerate overnight if desired.
Bake, covered, until set, 35-40 minutes. Meanwhile, make the streusel:
In a medium bowl, stir together the flour, brown sugar, and cinnamon. Add the butter and mash until mixture is crumbly.
When casserole is nearly done, top with streusel and sliced banana and bake uncovered until golden brown, 5-10 minutes. Enjoy!