Grease the bottom and sides of a 9×13-inch baking dish with cooking spray. Set aside.
Cut the French bread into 1 ½-inch cubes until you have about 12 cups. Place about ⅔ of the bread cubes into the prepared baking dish.
In a small bowl, combine the softened cream cheese and ⅓ cup sugar. Stir until smooth.
Spoon dollops of the cream cheese mixture over the first layer of bread cubes (there’s no need to spread it out evenly).
Sprinkle the raspberries over the bread and cream cheese, then top with the remaining bread cubes. Set aside.
In a large bowl, whisk the eggs until well beaten. Add the milk, ½ cup sugar, and vanilla extract, and whisk until fully combined.
Pour the egg mixture evenly over the bread cubes in the baking dish. Gently press the bread cubes down so they soak up some of the liquid.
Cover the casserole with a lid or plastic wrap and refrigerate overnight (or for several hours if preparing the same day).
When ready to bake, preheat the oven to 350°F (175°C).
Bake the casserole uncovered for 45-50 minutes, or until the internal temperature reaches 160°F and the top is golden brown.
Remove from the oven and let it rest for a few minutes. If desired, sprinkle with powdered sugar before serving. Serve with maple syrup for a delicious finishing touch.