Blueberry French Toast Casserole

Growing up, my mother assembled a breakfast casserole on Christmas Eve so that the next day, all she had to do was stick the baking dish in the oven, and our frenzied gift-wrapped strewn morning was filled with a warm, freshly baked breakfast that required zero attention from her. While the holidays are a great time to use time-saving strategies in the kitchen, preparing a meal the day before is a gift to your future self year-round. Overnight oats or cinnamon rolls might be the first thought that comes to mind when you think of a make-ahead recipe, but sometimes you don’t want cold oats or have time to let dough rise.

French toast casserole solves both problems since it comes together quickly and bakes into a warm carb-rich meal that is easily customizable. This recipe takes classic French toast ingredients like milk, sugar, and eggs and injects them with a heap of blueberries for a custardy, not-too-sweet breakfast (or brunch or dessert) that bakes while you relax. The key to loading the French toast with blueberry flavor starts with a blueberry-maple sauce that does double duty by being layered into the casserole during assembly and served on the side for spooning over each wedge.

Ready to try your hand at it? Keep reading on down below for all of my top tips.

How To Make Blueberry French Toast Casserole

INGREDIENTS

• Challah: Challah is an enriched, yeasted bread, meaning it has eggs and oil or butter added to the dough. These additions keep the bread soft and tender while imparting a rich and gentle eggy flavor that pairs deliciously with the custard and crisps in the oven without becoming hard. Brioche is very similar and would make a great substitute, though it can be sweeter and cakier than challah.
• Blueberries: You can’t have blueberry French toast without blueberries! These sweet-tart purple berries are available year round (always best freshly picked), but can vary in size, texture, and flavor. Skip the jumbo blueberries for this recipe and stick with regular-sized ones so they distribute better throughout the casserole. Blackberries or raspberries would make a delicious addition or substitution, but beware they have lots of seeds that can stubbornly lodge between your teeth.
• Pure Maple Syrup: Pure maple syrup is so much more than just a sweet syrup, and there are different versions with slightly different tastes. Maple syrup has a deep caramel flavor with hints of citrus, and robust syrup (formerly known as Grade B) has a slightly darker color and stronger taste that screams ‘maple’ and stands up to the flavor of the berries without becoming a one-note sugary taste.
• Orange: Blueberries pair so well with citrus, and many people automatically gravitate toward lemon, but don’t overlook what orange can bring to the dish. The fragrance and gentle bitterness in orange zest coupled with the sweet juice from the fruit lift up the flavor of the berries without sourness. Swapping in a blood orange would be a fantastic substitute and layer in even more purple color to the syrup.
• Butter: When you cook slices of French toast in a hot, buttered skillet, the butter seeps into the bread and crisps the edges. There is no reason to lose those benefits when making a French toast casserole, and dotting the top with cut up butter before baking is the easiest way. Since the custard and sauce already have salt in them, unsalted butter is the better choice, but with only 2 tablespoons in the recipe, salted butter will not drastically change the end result.
• Eggs: Eggs are a must in this recipe. In addition to providing flavor, they help bind the bread cubes together for a sliceable, cohesive casserole. Make sure to beat them well enough so there are no globs of separate egg white in the custard that will bake up bouncy.
• Whole Milk: There are times when the full-fat version is the best choice, and this is one of them. Using 2% milk will not be a fail, but the custard will skew more wet than creamy.
• Heavy Cream: Boosting the richness of the milk with some cream keeps the custard silky without making it too heavy. Plus, you will have more on hand to whip to soft peaks for topping.
• Turbinado Sugar: This raw, coarse sugar does double duty in the recipe. Because it’s less processed, it has a taste that’s closer to brown sugar than white, so it adds flavor and not just sweetness to the custard. Sprinkling some over the top before baking adds some crunch for a textural contrast to the soft interior.
• Pure Vanilla Extract: Vanilla may not make or break this recipe, but the warmth and subtle flavor it brings helps balance the custard in the same way that the pinch of salt does. While substituting the vanilla with another extract might be too intense, you can always add a splash of another extract, like almond or maple, in addition to the vanilla.
• Nutmeg: Nutmeg is the overlooked hero of the spice cabinet. It’s fragrant and gently spicy with woodsy, peppery, and citrusy notes. A hefty dose of freshly grated nutmeg in the custard offers a lot of flavor without dominating the other ingredients, the way cinnamon can. For a heavier spice, cinnamon, ginger, or apple pie spice blend will all offer that boost.
• Whipped Cream: Whipped cream is appropriate any time of day, and whipping it yourself means you can control the sweetness and flavoring of the cream. Between the casserole and the sauce, the whipped cream doesn’t need any sugar or vanilla, but you do you.
• Greek Yogurt: If whipped cream as a topping is a little too rich, Greek yogurt is the way to go. It’s creamy with a slight tang that cuts through the sweetness of the blueberry syrup.

STEP-BY-STEP INSTRUCTIONS

Spread the bread cubes on an unlined, un-greased baking sheet using your hands to fit them into a single layer. Bake until the bread is lightly toasted by feel, but not by color. The outsides of the cubes will feel dry but the bread will not be hard or crunchy.

As the berries cook, they will release their juices, loosening the consistency of the syrup and turning it purple. When the berries are all softened and at least half have lost their shape, the sauce is ready.

Scoop out 1/2 cup of the sauce and some cooked berries and transfer to a bowl. Add the remaining 1 cup blueberries and toss well to coat until glossy. Set aside until ready to assemble the casserole. Transfer the remaining sauce to a resealable container and refrigerate until you need it (you'll be serving it alongside the casserole).

Butter the bottom and sides of a 13" x 9" baking pan. Whisk the egg whites until even pale yellow with no stringy egg whites. (Do not skip this step or the custard will have a mottled look with bits of hard egg whites separate from the custard.) Add milk, cream, sugar, vanilla, nutmeg, and salt and whisk gently but thoroughly to dissolve the sugar.

Add the bread cubes, in two batches if it’s easier depending on the size of the bowl, and toss well until the bread is coated and soaked, but there is still some custard in the bowl.

Spread enough bread in the baking dish to make an even layer, about two-thirds, and spoon the blueberry mixture over top including any syrup in the bowl. Top with the remaining bread. It will not fully cover the berries. Press with your hands or a spatula to remove any large pockets of air and make a level height. Scatter the butter pieces over top, cover, and refrigerate overnight, 10 to 12 hours.

Let the casserole and sauce sit on the counter while the oven preheats to 350° so they each lose some of the chill from the refrigerator. Uncover the casserole and sprinkle the remaining 1 tablespoon sugar over the top of the casserole. Bake until the casserole is well puffed, especially in the center, about 45 minutes. The baking dish will be full. The edges will be bubbling and crisp, though the top will not brown very much. Let cool at least 5 minutes. The casserole will deflate slightly.

Cut the casserole into large squares using a knife or a metal spatula (it’s soft so you don’t need a super sharp blade) and lift the squares onto plates. Spoon the sauce, both syrup and berries, over the French toast as much or as little as desired. Top with whipped cream or Greek yogurt. 

Full list of ingredients and directions can be found in the recipe below. 

Recipe Tips

• You can make the custard in a blender instead of whisking in a bowl, but be careful not to overwhip it. Pulse or blend the eggs on low speed as you want to combine them well but not create a thick emulsion. Take the same approach after adding the dairy so the cream does not begin to whip.

• If you're looking to replace the milk and cream with a non-dairy substitute, consider the ingredients as well as the viscosity. Some plant-based milks have added sugar that could make the casserole too sweet. An unsweetened barista blend or non-dairy creamer is a good replacement for the heavy cream as these will be thicker and richer, preventing the casserole from tasting soggy.

• Instead of one large baking pan, you can divide the bread and saucy blueberries between 8 ovenproof large ramekins or baking dishes to make this casserole single serve.

Storage

As with most casseroles, this recipe can feed a crowd, but it also works for a party of just a few. Leftovers can be stored right in the baking dish it was cooked in, covered, or transferred to smaller storage containers and refrigerated up to 3 days.