Preheat your oven to 350°F (175°C) and grease a 9×13-inch baking dish with butter.

Cut the croissants into large chunks and layer half in the baking dish, sprinkling half of the chocolate chips over them. Repeat with the remaining croissants and chocolate.

Whisk the eggs in a mixing bowl, then mix in the milk, cream, sugar, vanilla, salt, and cinnamon until combined.

Pour the custard mixture over the croissants, pressing them gently into the custard. Allow to sit for 10 to 15 minutes, or refrigerate overnight.

Bake uncovered for 35 to 40 minutes until the top is puffed and golden brown.

Let cool for 10 minutes before dusting with powdered sugar and serving warm.