01 - Grease a 9 x 13 inch baking dish thoroughly. Spread half of the bread cubes in an even layer across the bottom of the dish.
02 - Scatter cream cheese cubes and half the blueberries evenly over the bread layer. Top with remaining bread cubes, then distribute the remaining blueberries over the surface.
03 - In a mixing bowl, whisk together eggs, milk, heavy cream, granulated sugar, and vanilla extract until fully combined and smooth.
04 - Pour the egg mixture evenly over the bread and berries. Press down gently with your hands or a spatula to ensure all bread pieces absorb the liquid. Cover the dish and refrigerate for at least 30 minutes, or overnight for optimal results.
05 - Preheat oven to 350°F.
06 - In a small bowl, combine softened butter, brown sugar, flour, cinnamon, and salt. Mix with a fork until the mixture reaches a crumbly texture.
07 - Sprinkle the streusel mixture evenly over the casserole. Bake uncovered for 40 to 45 minutes until the top is golden brown and the center is set.
08 - Allow the casserole to cool for 5 to 10 minutes before serving. Dust with powdered sugar if desired.