Preheat your oven to 350°F (175°C). This will ensure your casserole bakes evenly and becomes perfectly golden.

Combine in a large bowl the bread chunks, eggs, milk, heavy cream, granulated sugar, brown sugar, vanilla extract, and ground cinnamon. Whisk until everything is well incorporated and creamy.

Fold in the chopped bananas gently until they are evenly distributed throughout the mixture.

Pour the mixture into a greased casserole dish, spreading it out evenly to allow for even cooking and perfect texture.

Mix in another bowl the flour, brown sugar, and cinnamon for the streusel topping.

Cut in the unsalted butter pieces using a pastry cutter or fork until the mixture resembles coarse crumbs. Sprinkle this delightful streusel over the casserole.

Bake in the preheated oven for 45-50 minutes, or until the top is set and golden brown.