Grease a 6x6 baking dish with butter. Cut the Croissants into small cubes (9-12 cubes per slice)
In a large bowl, combine the eggs, cream, sugar and lemon extract. Whisk until they are well combined to make a custard. Set aside.
Spread the cut Croissants pieces in a single layer in the baking pan. Spread a handful of berries on the brioche.
Now add another layer of brioche and then spread more berries on it.
Now pour the custard spreading it all over the Croissants.
Press with a spatula, so that all the Croissants is soaked in the custard. Keep aside for 10 minutes to let the custard soak in the Croissants.
Bake for about 40-50 minutes at 350°F or until the center is set.