Cut bread into cubes or chunks. Place into a 9 x 13 casserole dish spread with cooking spray.
In medium bowl combine brown sugar and 1 egg. Whisk together until they are combined.
Whisk in the rest of the eggs then stir in vanilla extract, vanilla greek yogurt, lemon juice, and lemon rind. Stir until all of the ingredients are combined.
Pour ego mixture over the bread and stir until combined.
Stir in the blueberries.
Using a spoon push down the bread into the egg mixture.
Cover with foil or plastic wrap and then place in the refrigerator for 2 hours or overnight.
When ready to bake, preheat the oven to 350 degrees and then take the casserole dish out of the refrigerator and let it sit on the counter for about 20 minutes.
Bake for 50 minutes or until the french toast is set.
Let it cool for 3-5 minutes and serve warm with pure maple syrup.