Cut 1/2-inch off both ends of bread and discard (or eat). Cut loaf into 1-inch slices then cut each slice into 1-inch cubes (I cut the loaf in half first then kept the cubes from each half separate so it would be easier to determine half). Spread half of the bread cubes into an even layer in a buttered 13 by 9-inch baking dish, set aside remaining bread cubes.
In a small bowl, using an electric hand mixer, blend together Nuefchatel cheese, powdered sugar and 1/2 tsp vanilla. In a separate bowl stir together lemon zest and 1 Tbsp sugar. Using a rubber spatula and a clean fingertip, spread Nuefchatel cheese mixture over bread cube layer in baking dish. Sprinkle blueberries over Nuefchatel cheese layer then sprinkle lemon zest mixture evenly over blueberry layer. Spread remaining bread cubes into an even layer over top of blueberries.
In a blender, blend together eggs, milk, remaining 1/4 cup sugar and remaining 1 tsp vanilla on low speed until well blended, about 10 seconds. Slowly pour mixture evenly over top of bread cubes in baking dish. Cover with plastic wrap and refrigerate 8 hours or overnight.
The following morning, remove baking dish from refrigerator and allow to rest at room temperature for 30 minutes. Preheat oven to 350 degrees during the last 10 minutes of resting.
Remove plastic wrap. Cover baking dish with aluminium foil and bake in preheated oven 30 minutes, then remove foil and continue to bake 25 - 35 minutes, until golden brown (if it is becoming too golden brown but isn't cooked through then you can cover with foil again during the last few minutes of baking). Allow to rest 5 minutes, then cut into servings and serve warm topped with blueberry syrup and sweetened whipped cream if desired.
*Regular cream cheese would also work, but I'd recommend likely thinning out the cream cheese mixture with 1 to 2 Tbsp milk to make it a more spreadable consistency.