In a skillet, melt the butter over medium heat. Add the beaten eggs, salt, and pepper, and scramble until fully cooked.

Add the spinach to the skillet and cook until wilted. Remove from heat.

Slice each croissant in half horizontally.

Layer the ham, cheese, and scrambled egg mixture on the bottom half of each croissant.

Top with the other half of the croissant and press gently.

Preheat the oven to 350°F (175°C). Place the assembled sandwiches on a baking sheet.

Bake for 10 minutes or until the cheese is melted and the croissants are warm.