Cut the French bread into 1-inch cubes. If it’s not stale, leave the cubes on a tray overnight to dry out. Stale bread soaks up the custard better, giving you that perfect mushy yet firm texture.
Grease your baking dish and spread the bread cubes evenly in it. Next, layer the sliced bananas across the bread pieces. This adds sweetness and that signature banana flavor in every bite.
Whisk together eggs, milk, heavy cream, brown sugar, vanilla, cinnamon, and a pinch of salt in a bowl. Pour this tasty mixture over the bread and bananas. Give the bread a gentle press to help it soak up all the liquid goodness.
Cover the baking dish tightly with plastic wrap and refrigerate it for at least 2 hours, or ideally overnight. This step is crucial to help the flavors meld together beautifully.
Preheat your oven to 350°F (175°C). While waiting, prepare the brown sugar topping by mixing flour, brown sugar, and cubed butter until crumbly. Use your fingertips for the best texture.
Remove the casserole from the fridge, sprinkle the topping evenly over it, and bake for 45-55 minutes. It’s ready when the top turns golden brown, and the casserole is set. Serve warm with a dusting of powdered sugar or a drizzle of maple syrup.