Grease a 9x13 inch baking dish with butter or cooking spray. Layer half of the bread cubes evenly at the bottom of the dish.

In a mixing bowl, beat the softened cream cheese until creamy. Gradually add the confectioners' sugar and 1/4 teaspoon of vanilla extract, mixing until smooth.

Carefully add the remaining bread cubes over the cream cheese mixture, pressing down gently.

In a large bowl, whisk together the eggs, remaining milk, ground cinnamon, brown sugar (2/3 cup), and remaining vanilla. Mix until smooth.

Cover the baking dish tightly with plastic wrap and refrigerate for at least 3-4 hours, or ideally overnight.

Preheat your oven to 350°F (177°C) about 30 minutes before baking.

In a separate bowl, combine brown sugar (1/3 cup), all-purpose flour, and ground cinnamon. Cut in cold cubed unsalted butter until the mixture resembles coarse crumbs.

Remove the plastic wrap from the casserole and sprinkle the topping evenly over the surface. Bake uncovered for 45-55 minutes or until golden brown.