Sourdough Blueberry Overnight French Toast

This is a sweet, custardy French toast bake, great for a brunch or a nice family breakfast. The pops of blueberry and crumble topping really set this French toast bake apart from others. I decided to add a little sourdough discard to the crumble topping and let it sit overnight so the flour in there ferments, just like the bread used in the bake. This way, the whole thing is fermented and more easily digestible. I used half a loaf of bread and baked it in an 8x8 pan. The recipe can easily be doubled and baked in a 9x13 pan for a larger crowd.