This Overnight Baked Banana French Toast Casserole has become my go-to for slow weekend mornings and special breakfasts. I first discovered this combination one sleepy holiday morning when I wanted something that could be assembled the night before so I could enjoy the morning with my family instead of standing at the stove. The final dish is everything I hoped for: the bread soaks up a rich custard, the bananas lend natural sweetness and a tender texture, and a buttery streusel added at the end gives a crisp, caramelized contrast to the soft interior.

I love how forgiving the method is — you can use day-old sourdough, a rustic French loaf, or even a country-style boule. The custard, made from eggs, whole milk and a little heavy cream, produces a custardy, almost crème-like interior without being soggy. When we pulled this from the oven that first time, the top was perfectly golden and the house smelled like warm bananas, vanilla and cinnamon; my partner declared it brunch royalty, and the kids requested it for every birthday after.

Ingredients

• Sourdough or French bread (1 lb): Choose a day-old loaf if possible; slightly stale bread soaks the custard without turning mushy. I like an artisan sourdough for its tang and texture — about 1 pound yields hearty chunks that keep some structure.
• Large eggs (8): Whole eggs provide structure and richness to the custard; room temperature eggs incorporate more smoothly and help avoid thermal shock when baking.
• Whole milk (2 cups): Adds body and tenderizes the crumb. You can use low-fat milk, but the dish will be less rich.
• Heavy cream (1/2 cup): Boosts creaminess and gives the interior a silky mouthfeel; if you want lighter results, substitute with an extra 1/2 cup milk.
• Granulated sugar (1/2 cup): Balances the banana’s natural sweetness and helps caramelize the top. For a less-sweet version reduce to 1/3 cup.
• Bananas (6–7 medium, chopped): Use ripe but not overly mushy bananas — they should be aromatic and yellow with some brown speckles for optimal sweetness and texture.
• All-purpose flour (3/4 cup) for streusel: Forms the dry base of the topping; measure by spooning flour into the cup and leveling for accuracy.
• Salted butter (1/2 cup, 1 stick): Cold butter cut into the streusel yields small crumbs when mixed; you can use unsalted and add a pinch of salt if preferred.
• Brown sugar (1/2 cup) for streusel: Adds molasses notes and helps the streusel caramelize; packed measurement gives consistent results.
• Ground cinnamon and vanilla extract (to taste): Use 1–2 teaspoons cinnamon and 1 teaspoon vanilla in the custard for warm flavor; adjust to preference.

Instructions

Grease the dish: Use a 9×13-inch casserole dish and coat it thoroughly with butter or nonstick spray so the finished pieces release easily. Greasing also helps the bottom brown. (Visual cue: the entire interior should gleam with a thin film of fat.) Prepare the bread: Cut 1 pound of sourdough or French bread into 1–1.5 inch chunks and place them in a large mixing bowl. If your bread is very fresh, toast the cubes at 350°F for 8–10 minutes to dry slightly; this prevents a gummy center. Make the custard: In a separate bowl, whisk together 8 large eggs, 2 cups whole milk, 1/2 cup heavy cream, 1/2 cup granulated sugar, 1 teaspoon vanilla extract, and 1–2 teaspoons ground cinnamon until smooth and homogenous. Whisk vigorously for about 30 seconds to incorporate air, which helps a lighter texture. Combine bread, bananas and custard: Pour the custard over the bread cubes, then fold in 6–7 chopped bananas gently to avoid crushing them. Stir just enough to combine — the bread should be saturated but not falling apart. Let the mixture sit for 5–10 minutes to begin absorbing the custard before transferring. Refrigerate overnight: Transfer the soaked mixture to the greased 9×13-inch dish, spread evenly, cover tightly with plastic wrap or foil, and refrigerate at least 8 hours or overnight. The prolonged soak allows deep flavor penetration and a custardy interior. Bake the casserole: The next morning, preheat the oven to 350°F (176°C). Remove the plastic wrap and place the dish on the middle rack. Bake uncovered for 35–40 minutes until the edges are bubbling and the top is golden brown; a toothpick inserted into the center should come out mostly clean with a few moist crumbs. Prepare and add streusel: For the streusel, cut 1/2 cup cold salted butter into small pieces and mix with 3/4 cup all-purpose flour, 1/2 cup packed brown sugar, and 1/2 teaspoon cinnamon until the texture resembles coarse crumbs. Sprinkle the streusel evenly over the casserole during the final 5 minutes of baking so it crisps without overbrowning. Rest and serve: Allow the casserole to rest 10–15 minutes after baking so it firms up slightly, then slice and serve warm. Optional finish: dust lightly with powdered sugar or drizzle maple syrup just before serving.

Storage Tips

Store leftovers in an airtight container in the refrigerator for up to 4 days. To reheat, place slices on a baking sheet and warm at 325°F for 8–12 minutes so the interior warms evenly without drying out. For best texture when freezing, assemble and freeze before baking; wrap tightly in foil and label with the date. When ready to bake from frozen, thaw in the refrigerator overnight if possible, or bake covered at 350°F and add 15–20 minutes to the baking time. Avoid microwaving for long periods, as this can make the custard rubbery; brief microwave spurts followed by oven finishing work well for single portions.

Ingredient Substitutions

If you don’t have sourdough, a crusty French bread, challah or brioche works beautifully — brioche will make the interior richer. For dairy-free adaptions, use unsweetened almond or oat milk and replace heavy cream with full-fat coconut milk; omit butter in the streusel and use coconut oil or vegan butter. To reduce sugar, swap half the granulated sugar with a natural sweetener like maple syrup, reducing the milk slightly to compensate. If you’re out of bananas, pear slices or apple thin slices make a lovely autumn variant — toss them in a little lemon juice and cinnamon before folding in.

Serving Suggestions

Serve warm slices with a drizzle of real maple syrup, a spoonful of Greek yogurt for tang, or a scattering of toasted nuts for crunch. For a brunch spread, pair with crisp bacon, a green salad with citrus vinaigrette, or a simple frittata. Garnish with fresh banana slices, a dusting of powdered sugar, or a few raspberries for color. It’s equally fitting as an after-dinner treat with a small scoop of vanilla ice cream and a cup of coffee.

Cultural Background

Layered custard-and-bread dishes appear across many kitchens — from European strata to Southern bread pudding. This dish blends the American love for French toast with the British and French tradition of soaked bread desserts. The overnight soak is a practical technique rooted in making the most of stale bread and turning it into something celebratory. The streusel topping nods to Central European crumb-topped bakes, adding texture and sweetness to a custardy base.

Seasonal Adaptations

In winter, swap bananas for poached pears and add star anise or nutmeg to the custard. For late summer, fold in berries with the bananas and reduce added sugar slightly. During holidays, stir a tablespoon of orange zest and a splash of bourbon into the custard for festive depth. The flexibility of the base makes it easy to adapt to whatever produce is in season.

Meal Prep Tips

Assemble multiple casseroles in disposable foil pans for gifting or feeding a crowd. Portion leftovers into single-serve containers and refrigerate — they reheat very well and make convenient breakfasts for busy weekday mornings. Keep the streusel separate and add it during the final bake or crisp-up step to maintain maximum crunch. Label containers with assembly and freeze dates to ensure food safety.

In short, this overnight baked banana casserole rewards a little night-before prep with effortless morning payoff. It’s a warm, welcoming dish that’s perfect for sharing — try it the next time you want a relaxed, crowd-pleasing brunch that still feels homemade and thoughtful.