Preheat oven to 375°F and grease a 9×9-inch baking dish with butter. Set aside.

Add the egg yolks, milk, cream, sugar, vanilla, and salt to a large bowl and whisk until combined.

Add croissant pieces to the egg mixture and toss to coat, making sure croissants are well-moistened. Stir in 3/4 of the chocolate chips.

Pour mixture into prepared baking pan and top with remaining chocolate chips.

Bake until a toothpick inserted into the center comes out clean, 50-55 minutes. If bake starts to brown too much, cover loosely with foil.

Serve warm and enjoy!