Preheat your oven to 350°F (175°C). Grease a 9x13-inch baking dish with butter or non-stick spray.
Place the cut chocolate croissants evenly in the prepared baking dish.
In a large mixing bowl, whisk together the eggs, whole milk, granulated sugar, vanilla extract, ground cinnamon, and salt until well combined.
Pour the egg mixture over the croissant pieces, ensuring all pieces are soaked. Gently press down with a spatula to help the croissants absorb the liquid.
Sprinkle the semi-sweet chocolate chips evenly over the top.
Allow the mixture to sit for about 15 minutes to soak in, or refrigerate for up to 2 hours if you prefer to prepare it in advance.
Bake in the preheated oven for 30-35 minutes, or until the top is golden brown and the custard is set.
Remove from the oven and let it cool for about 5 minutes. Dust with powdered sugar before serving, if desired.