• Preheat your oven to 350°F and grease a 9x13 baking dish with gluten-free cooking spray.
• Cut 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.
• In a large measuring cup or medium-sized bowl, whisk 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.

Crumb Topping

• 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 the casserole and seeing 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.

Glaze

• Mix the ingredients for the glaze in a small bowl until they're nice and smooth. Allow the casserole to cool for a few minutes before drizzling glaze over it and serving. Enjoy!