In a bowl, whisk together the eggs, milk, salt, and pepper until well combined.

Heat a skillet over medium heat and pour in the egg mixture. Cook, stirring gently, until the eggs are scrambled and set.

Slice the croissants in half. Layer the scrambled eggs, cheese, bacon, and spinach on the bottom half of each croissant. Top with the other half.

Place the assembled sandwiches in the skillet or oven for a few minutes until the croissants are warm and the cheese is melted.