01 - Preheat the oven to 350°F. Grease a 9 x 13-inch baking dish with butter or nonstick spray.
02 - Arrange the croissant pieces evenly in the prepared dish.
03 - In a medium bowl, beat the cream cheese with ½ cup sugar and vanilla extract until smooth and creamy.
04 - Drop spoonfuls of the cream cheese mixture over the croissants, distributing as evenly as possible. Sprinkle the blueberries evenly over the top.
05 - In a separate large bowl, whisk together eggs, milk, heavy cream, ¼ cup sugar, cinnamon, and salt until well combined.
06 - Pour the egg mixture evenly over the croissants, pressing down gently to ensure all pieces are moistened.
07 - Drizzle the melted butter over the top and sprinkle with coarse sugar, if using.
08 - Cover the dish with foil and bake for 30 minutes.
09 - Remove the foil and bake an additional 15 minutes, or until the casserole is golden and set.
10 - Let cool for 10 minutes before serving. Serve warm, optionally with powdered sugar or maple syrup.