1. Preheat the oven to 350 F and place 6 croissant halves on a large rimmed baking sheet. On each croissant half, place one piece of cheese, topped by one piece of ham.
2. In a large non-stick pan or cast iron pan, melt the butter over medium-high heat. Crack the eggs into a large mixing bowl, then break up the yolks and gently whisk with a fork. Add the milk and whisk again. Once the butter is melted, pour the eggs into the pan. Using a spatula, gently move the eggs around from time to time, cooking them up (scrambled eggs). Season with salt and pepper, to taste. Remove the eggs from heat.
3. Divide the eggs between each croissant half. Place the top croissant half on top of the eggs, for each croissant. Place the baking tray into the oven and bake for 8- 10 minutes, until the cheese is melty. Serve immediately.

If you’re planning on freezing the sandwiches, allow them to completely cool before individually wrapping them in plastic wrap and placing them in the freezer, for up to 2 months. To reheat, unwrap the frozen croissant, place it on a plate and microwave for 1 minute, OR, place the frozen croissant on a baking sheet and bake in an oven preheated to 300 F for 10-12 minutes.