This Overnight Birthday Cake French Toast Casserole is the ultimate celebration breakfast, bringing the nostalgic flavor of a Funfetti cake straight to your morning table. By combining sturdy bread chunks with a rich, cake-mix-infused custard, this dish transforms a traditional brunch staple into a vibrant, sprinkle-filled treat that feels like a party in every bite.
Prepared the night before and baked to golden perfection, this decadent casserole is finished with a buttery cake-mix streusel and a drizzle of warm rainbow chip frosting.
Recipe Details
- Flavor Profile: Sweet and vanilla-forward with the classic birthday cake essence, balanced by warm notes of cinnamon and tangy sourdough.
- Textures: A soft, custardy center contrasted by a slightly crisp, buttery streusel topping and colorful, crunchy sprinkles.
- Total Time: 15 minutes of prep, an overnight soak (8-12 hours), and approximately 35-55 minutes of baking.
- Difficulty: Easy. This is a simple assemble-and-bake recipe that is perfect for hosting a crowd or celebrating a special morning.
What You’ll Need
This celebratory dish is built on a foundation of hearty bread soaked in a specialized cake-batter custard. You will need a loaf of sourdough or French bread, a variety of dairy including milk and heavy cream, a box of Funfetti cake mix for both the custard and the streusel, and plenty of rainbow sprinkles to complete the look.
Ingredient Notes
- Sourdough or French Bread – Using a sturdy loaf is crucial. These types of bread hold their shape during the overnight soak without becoming too mushy.
- Funfetti Cake Mix – This provides the signature birthday cake flavor and sweetness for both the custard base and the crumbly topping.
- Heavy Whipping Cream – Adding cream alongside the milk ensures a luxurious, velvety custard that tastes professional.
- Rainbow Sprinkles – These are added before the overnight soak to ensure the color is distributed throughout the top of the casserole.
- Rainbow Chip Frosting – Heating this in the microwave creates a pourable glaze that mimics the look of a traditional birthday cake.
Add-ins and Substitutions
- Fruit: You can toss in a handful of fresh blueberries or sliced strawberries before baking for a fruity cake twist.
- Nuts: For a bit of extra crunch, add 1/2 cup of white chocolate chips or slivered almonds to the bread mixture.
- Syrup: If the frosting is too sweet for your taste, a high-quality maple syrup provides a more traditional breakfast finish.
How to Make Overnight Birthday Cake French Toast Casserole
1. Prep and Soak
Begin by greasing a 9×13 inch casserole dish. Place your sourdough or French bread chunks into a large bowl and set aside. In a separate large bowl, whisk together the eggs, milk, heavy cream, 2 cups of the Funfetti cake mix, cinnamon, and vanilla extract until smooth. Pour this egg mixture over the bread chunks and gently stir to ensure every piece is coated. Transfer the mixture to your prepared dish, spreading it into an even layer. Evenly scatter the sprinkles over the top, then cover the dish and refrigerate overnight.
2. The First Bake
When you are ready to serve the next morning, preheat your oven to 350 F (176 C). Place the chilled casserole into the oven and bake for 25-30 minutes.
3. Add the Streusel
While the casserole is in the oven for its initial bake, prepare the topping. In a small bowl, cut the remaining 1 cup of cake mix into the 1/2 cup of salted butter pieces using a pastry cutter or your fingers until the mixture becomes crumbly. Remove the casserole from the oven, evenly crumble the streusel over the top, and return it to the oven.
4. Final Bake and Serve
Continue baking for another 10-25 minutes, depending on your desired level of doneness. Once golden and set, remove from the oven. Serve warm with maple syrup or melted Rainbow Chip frosting.
Pro Tip: If your bread is very fresh, cut it into chunks and leave them out on the counter for a few hours before assembling. Stale bread absorbs the cake-mix custard much better, resulting in a more flavorful and less soggy center.
Recipe Tips
- Grease Generously: Make sure to grease the corners of your 9×13 dish well, as the cake mix in the custard can cause the edges to stick.
- Uniform Chunks: Cut your bread into consistent 1-inch cubes so that they absorb the liquid at the same rate.
- Melting the Frosting: To use the frosting as a glaze, remove the lid and foil seal, and microwave in 15-second intervals until it reaches a thin, pourable consistency.
- Check for Doneness: The bake time varies; look for the center to be set (not liquidy) and the streusel to be a light golden brown.
FAQs
Can I use a different flavor of cake mix? Yes! While Funfetti is traditional for birthday cake, you can follow the exact same method with chocolate, strawberry, or lemon cake mix for a different flavor profile.
What if I don’t have overnight? While the overnight soak is recommended for the best texture, you can let it sit for at least 2 hours in the fridge if you are in a hurry, though the bread may not be as custardy.
How do I store leftovers? Store any remaining casserole in an airtight container in the refrigerator for up to 3 days. Reheat individual portions in the microwave or oven.
Serving Suggestions
- Whipped Cream: A large dollop of fresh whipped cream and extra sprinkles makes this look even more like a real cake.
- Fresh Berries: Serve with a side of tart raspberries or blackberries to balance the sweetness of the cake mix.
- Crispy Protein: Balance the sweet flavors with a side of salty turkey bacon or savory sausage.
Make This Recipe in Advance
This recipe is designed to be made in advance! You must assemble the casserole and let it soak in the refrigerator for at least 8 hours (overnight) to achieve the correct consistency. The streusel can also be prepped the night before and kept in a sealed bag in the fridge, so all you have to do in the morning is preheat the oven and bake. This makes it an ideal stress-free breakfast for birthdays or holiday mornings.
Overnight Birthday Cake Funfetti French Toast Casserole
- Total Time: 70 minutes
- Yield: 10 servings 1x
- Diet: Vegetarian
Description
A vibrant twist on a brunch classic that brings the nostalgic flavor of Funfetti cake to the breakfast table. Hearty bread is soaked in a rich, cake-mix-infused custard overnight, then baked with a buttery streusel and drizzled with rainbow chip frosting.
Ingredients
For the Casserole
- 1 loaf sourdough or French bread (1-inch chunks)
- 8 large eggs, 2.5 cups milk, 0.5 cup heavy cream
- 2 cups Funfetti cake mix, 2 tsp cinnamon, 2 tsp vanilla
- 5 tbsp rainbow sprinkles
For the Streusel Topping
- 1 cup Funfetti cake mix
- 1/2 cup cold salted butter (cubed)
For Serving
- Melted rainbow chip frosting or maple syrup
Instructions
Soak: Grease a 9×13 pan. Whisk eggs, milk, cream, 2 cups cake mix, cinnamon, and vanilla. Pour over bread chunks in the pan; toss to coat. Top with sprinkles, cover, and chill 8–12 hours.
First Bake: Preheat oven to 350°F. Bake casserole uncovered for 25–30 mins.
Streusel: Work cold butter into 1 cup cake mix until pea-sized crumbs form. Sprinkle over the partially baked casserole.
Final Bake: Bake 15–25 mins more until set and golden. Rest 5 mins.
Serve: Drizzle with melted frosting or syrup.
Notes
Stale Bread is Best: Dry or stale bread absorbs the custard much better than fresh bread, preventing a soggy center.
Frosting Tip: Microwave the frosting in short bursts until it reaches a ribbon-like consistency for a professional ‘cake glaze’ look.
Storage: Refrigerate leftovers for up to 3 days; microwave slices for 30–45 seconds to reheat.
- Prep Time: 15 minutes
- Cook Time: 55 minutes
- Category: Breakfast
- Method: Baking
- Cuisine: American
Nutrition
- Serving Size: 1 square
- Calories: 485
- Sugar: 32
- Sodium: 580
- Fat: 22
- Saturated Fat: 12
- Unsaturated Fat: 10
- Trans Fat: 0
- Carbohydrates: 62
- Fiber: 2
- Protein: 12
- Cholesterol: 185
Keywords: birthday cake french toast, overnight breakfast casserole, funfetti french toast, cake mix breakfast, sprinkle french toast
