Grease a 9x13-inch baking dish and add the chopped croissants.
In a small bowl, whisk together the cocoa powder, espresso powder, and melted butter until a smooth paste forms.
In a large mixing bowl, whisk together the eggs, egg yolks, heavy cream, milk, vanilla, cinnamon, salt, granulated sugar, and brown sugar.
Add 3–4 tablespoons of the custard mixture to the cocoa paste and gently whisk until smooth. This helps loosen the cocoa mixture and allows it to blend easier into the custard.
Slowly whisk the cocoa mixture into the remaining custard until fully combined.
Stir in the semi-sweet and dark chocolate chips.
Pour the custard evenly over the croissants, pressing gently so all pieces absorb the liquid.
Cover and refrigerate for at least 2 hours, preferably overnight.
Preheat oven to 375°F.
Sprinkle additional chocolate chips and turbinado sugar over the top.
Cover with foil and bake for 35–40 minutes.
Remove foil and continue baking for 20–25 minutes until golden brown and just set in the center.
Allow to cool for 10–15 minutes before serving.
Serve warm with whipped cream, espresso whipped cream, caramel sauce, hot fudge sauce, or vanilla ice cream.