01 - Preheat your oven to 375°F. Line a baking sheet with parchment paper.
02 - Cut the croissants in half horizontally and arrange them, cut side up, on the baking sheet.
03 - In a medium bowl, whisk together eggs, milk, salt, and pepper until well combined.
04 - Melt butter in a nonstick skillet over medium-low heat. Pour in the egg mixture and gently scramble, stirring with a spatula, until just set but still slightly creamy. Remove from heat.
05 - Place a slice of ham and cheese on the bottom half of each croissant. Top with a generous spoonful of scrambled eggs. Add tomato, avocado, and chives if desired.
06 - Replace the croissant tops and gently press down.
07 - Warm the assembled sandwiches in the oven for 5–7 minutes, or until cheese is melted and croissants are crisp.
08 - Serve immediately.