Leave bread out for a few hours or place it on a tray at 350˚F for about 8 minutes to slightly dry out.
In a medium bowl, combine cream cheese and sugar until fluffy.
Grease a 9x9 inch baking dish. Layer half of the bread cubes in the pan. Top with cream cheese mixture and half of the blueberries. Top with remaining bread and blueberries.
In a bowl, stir together the eggs, milk, syrup, and lemon zest until well mixed. Pour over the bread cubes, cover with foil and refrigerate overnight.
Remove the casserole from the fridge about 45-50 minutes before baking.
Preheat oven to 350°F.
Mix topping ingredients together in a small bowl. Sprinkle over casserole just before baking.
Bake uncovered 45-50 minutes or until a knife inserted in the center comes out clean and is hot.