Grease a 9x13 baking dish with nonstick cooking spray and arrange half of the bread cubes in the bottom.
In a large bowl and with an electric mixer on medium speed, beat the softened cream cheese, powdered sugar, lemon juice and 1 teaspoon lemon zest. Spoon it onto the bread cubes and spread it out evenly. Top with blueberries and then add the rest of the bread cubes.
In another bowl, whisk together the eggs, milk, maple syrup, salt, vanilla, another dash of lemon juice and a teaspoon of lemon zest until well combined. Pour the mixture over the bread cubes and press it all down to make sure that everything gets soaked.
Cover the dish and refrigerate overnight or for at least 4 hours.
When you are ready to bake, pull it out and let it come to room temperature while the oven preheats to 350 degrees F.
Bake for 45 minutes or until the bread is all puffy, golden and the edges are crispy. The middle should be fully cooked and not appear wet or soggy.