Preheat oven to 350 F.

Spray a 9" x 13" pan with non-stick spray.

Add the croissants to the pan. Top with the blueberries.

Place the cream cheese, sugar, eggs, and vanilla in a large bowl. Beat with a hand-held blender until smooth. You can also use a counter-top blender.

With the blender still running, slowly pour in the milk. Blend until smooth.

Pour milk mixture over the croissants.

Let set on the counter for 20 minutes.

Bake for 35-45 minutes. Start checking after 30 minutes to make sure the top doesn't get too dark. If it does, cover it with foil and continue baking until cooked through.

Serve sprinkled with powdered sugar.