Overnight French Toast Casserole has all the goodness of French toast and then some thanks to that sweet crumble topping! It's made with a rich, cinnamony custard soaked sourdough bread and even the pickiest eaters will love it. It makes perfect holiday or weekend breakfast, and you'll love that you can make it the night before serving!
For the French toast: Butter a 13 by 9-inch baking dish. Add bread cubes to baking dish spreading them into an even layer. In a mixing bowl with a pour spout** whisk together sugar, cinnamon and nutmeg.
Add in eggs and whisk until well blended, while scraping bowl. Pour in milk, half and half and vanilla and whisk until well blended.
Slowly and evenly pour egg mixture over bread cubes working to coat all of them (if you miss a few just turn and dunk them into the custard that's in the dish). Cover with plastic wrap and chill overnight, or at least 10 hours.
In the morning preheat oven to 350 degrees and while oven is preheating remove casserole from fridge and let rest at room temperature, it should rest about 15 minutes. Also, prepare crumble while oven is preheating.
For the crumble: In a medium mixing bowl whisk together flour, brown sugar, cinnamon and salt.
Add butter and cut into flour mixture using a pastry cutter or a long pronged fork until mixture resembles coarse crumbs, transfer to fridge if oven hasn't fully preheated yet then add it just before placing casserole in oven.
Sprinkle casserole evenly with crumble then bake in preheated oven until set and center is cooked through and no longer soggy, about 38 - 45 minutes.
Let cool a few minutes, pour melted butter over top, dust with powdered sugar if desired, then cut into squares and serve warm drizzling each serving with maple syrup.
Notes
*I recommend using hearty bread like La Brea. Hearty French bread can be used as well.
*For easier, less messy cutting transfer bread to a plastic bag if it's in a paper bag and let it sit for a day. It makes cutting easier and less messy.
**If you don't have a mixing bowl with a pour spout at the end mixing you can transfer the egg mixture to a liquid measuring cup with a pour spout and pour it from there.
The casserole itself isn't that sweet so don't leave off the maple syrup. Syrup is not included in nutritional info.