Preheat your oven to 350° F and grease a 9x13 baking dish with gluten-free cooking spray.
Cut one loaf of the gluten-free bread into small pieces. Spread the gluten-free bread pieces evenly on an ungreased baking sheet and bake for 5-10 minutes, until nicely toasted. Please watch your oven because all ovens are different. Remove from the oven when toasted and set aside.
Add the toasted bread to the pan and sprinkle the blueberries over the top of the bread.
In a large measuring cup or medium-sized bowl whisk together the eggs, milk, granulated sugar, lemon juice, lemon peel, and pure vanilla extract until well blended. Pour the egg mixture evenly over the bread pieces.
In a small bowl add the gluten-free flour, brown sugar, salt, and melted butter and mix until crumbly. Sprinkle the crumb mixture evenly over the top of the casserole.
Bake for 1 hour on the middle rack. You can see if it is done by inserting a toothpick into the center of casserole and see if it comes out clean. You will also see the sides of the casserole pulling away from the sides of the pan when it is done. The casserole will also be firm and not jiggly when it's done. Please watch your casserole because all ovens are different.
Mix all of the ingredients of the glaze together in a small bowl until it's nice and smooth. Allow the casserole to cool a few minutes before drizzling glaze on it and serving. Enjoy!
Cover or store left-overs in an air-tight container and refrigerate. Reheat the casserole in the microwave or oven. This breakfast casserole is even good cold. (I prefer this casserole cold)
This casserole can be made ahead (even overnight) of time and refrigerated before baking, but do not add the crumb topping until right before baking.
I used almond milk and Smart Balance butter for the dairy-free option. Schär gluten-free bread is also dairy-free.
This casserole can be made ahead of time and refrigerated before baking, but do not add the crumb topping until right before baking.
Cover or store leftovers in an air-tight container in the refrigerator.
To freeze: place your completely cooled casserole in a freezer friendly air-tight container. You can freeze it for several months. You can easily reheat the casserole in the oven at 350°F for 10-15 minutes or in the microwave.