Preheat your oven to 350°F (175°C).

Lightly coat a 9x6 or 9x11 inch deep baking dish with cooking spray.

Tear the croissants in half and arrange them cut-side up in the prepared dish. Cut the ham into thirds and intersperse it among the croissants.

Sprinkle the freshly shredded cheese evenly over the croissants and ham.

In a medium bowl, whisk together the eggs, half and half, Dijon mustard, and a pinch of salt until well-combined and frothy. Pour this egg mixture evenly over the layered croissants and ham.

Cover the dish with foil and refrigerate for at least 30 minutes, or up to overnight.

Once soaked, bake it covered with foil for 20 minutes. Then remove the foil and continue baking for 10-15 minutes.

Let it rest for 5 minutes before dusting with powdered sugar and serving.