Heat oven to 180c, 160 fan. Mix up the eggs, cream cheese, sugar and vanilla extract, adding the milk slowly whilst beating with an electric whisk, let it stand whilst you continue with the recipe.
Meanwhile, cut up the croissants into large chunks and place in a square 9 inch tin, sprinkle the blueberries on the croissants.
Pro tip: Try to spread the blueberries evenly as you don't want too many in one bite, and none in another!
Give the mixture a stir to make sure everything is combined before pouring evenly over the croissants, make sure to spread evenly across the whole tray. Bake for 35 minutes, as the croissants are already baked, so to stop them burning on top you will want to put tin foil on for the last ten minutes.
Cut into squares and dust with icing sugar to serve if eating straight away. If your saving them for breakfast leave to completely cool. Once cooled, cover with cling film before refrigerating.