01 - Preheat the oven to 350°F. Generously grease a 9 x 13-inch baking dish with butter or nonstick cooking spray.
02 - Spread the cut croissant pieces evenly across the bottom of the prepared baking dish.
03 - In a medium bowl, beat the softened cream cheese with ½ cup sugar and vanilla extract until completely smooth and creamy.
04 - Drop dollops of the cream cheese mixture over the croissants, distributing as evenly as possible. Scatter the blueberries evenly across the top.
05 - In a separate large bowl, whisk together the eggs, whole milk, heavy cream, remaining ¼ cup sugar, cinnamon, and salt until thoroughly combined.
06 - Pour the egg mixture evenly over the croissant pieces. Gently press down with a spatula to ensure all pieces absorb the liquid.
07 - Drizzle the melted butter over the surface and sprinkle with coarse sugar for a crunchy finish, if desired.
08 - Cover the dish tightly with aluminum foil and bake for 30 minutes. Remove the foil and continue baking for an additional 15 minutes until golden brown and set in the center.
09 - Allow the casserole to rest for 10 minutes before serving. Serve warm, optionally dusted with powdered sugar or drizzled with maple syrup.