Crumble the topping over the entire French toast casserole.
Cover the baking dish with aluminum foil, and bake at 350° F for about 45-50 minutes. Then uncover and bake an additional 15 to 20 minutes.*
Allow it to cool for at least 10 to 15 minutes after baking. Then slice it and serve it with powdered sugar, maple syrup, blueberry sauce/syrup, or more blueberries.
*While I use sourdough, which I get at Aldi or make homemade, you can use other types of bread, including plain old sandwich bread, Challah bread, French bread, brioche, gluten-free bread, etc. The choice is up to you. You want the bread to be at least a day old and somewhat stale, so the bread cubes will really soak up the egg mixture. This ensures you don't have any egg mixture just sitting off to itself making a mini quiche in your casserole. You can also dry the bread out a bit by opening up the bag the night before and letting it get air. Or spread the slices out on a baking sheet the morning of, and let sit in a low heat oven for just a bit to lose some of the moisture.*If you're wondering whether to use frozen blueberries over fresh, you likely would be fine to use frozen blueberries. Be aware, though, that using frozen fruit can add more moisture to whatever recipe you're making, so your baked French toast could end up a little on the mushy side.*Use whole milk for the best results.*Be sure to use real maple syrup, not table syrup.*Or a good gluten-free flour.*I prefer to refrigerate my overnight blueberry French toast overnight because it lets everything sit and soak into the bread a little longer, bringing out all of the wonderful flavors later on when baking. But sometimes I just want to bake it and be done. And that's ok too. ALTERNATIVE FRUIT OPTIONSWhile I use blueberries in this recipe, you could switch out the blueberries for strawberries, blackberries, raspberries, or other types of fruit. You could even combine blueberries with other berries or maybe even peaches.CAN YOU FREEZE FRENCH TOAST CASSEROLE?Yes, you can freeze a blueberry French toast casserole before or after baking. Just be sure it's either in an airtight container or covered with plastic wrap and aluminum foil to prevent freezer burn.Also, be sure to allow enough time for thawing in the refrigerator before baking. Bake time will vary, depending on whether or not your casserole was already baked before freezing.Re-heating after freezing…Allow time for the casserole to thaw in the fridge. Then cover with aluminum foil, and re-heat in a 350° F oven for about half an hour, or until it's warmed through.Re-heating after refrigerating…You can re-heat it in the oven or microwave. If you're in a hurry, it's easier and quicker to re-heat it in the microwave in 30-second intervals until it's heated through.