Preheat your oven to 350°F (175°C).
Cut the croissants into quarters and arrange them evenly in a greased 9x13-inch baking dish.
In a mixing bowl, whisk together the eggs, milk, heavy cream, granulated sugar, vanilla extract, ground cinnamon, and salt until fully combined.
Pour the egg mixture evenly over the croissant pieces, pressing down slightly to ensure they are soaked.
If using, sprinkle chocolate chips over the top of the mixture.
Cover the baking dish with aluminum foil and let it sit for at least 30 minutes, allowing the croissants to soak up the custard (or refrigerate overnight for best results).
Bake covered for 30 minutes, then remove the foil and bake for an additional 15 minutes, or until the top is golden brown and the center is set.
Let it cool for a few minutes before serving. Dust with powdered sugar if desired and serve with maple syrup.