Preheat your oven to 350°F (175°C) and grease a 9x13-inch baking dish.
Crumble the croissants into bite-sized pieces and spread them evenly in the dish.
In a large bowl, whisk together the eggs and milk.
Add the shredded cheese, bell peppers, onions, salt, and pepper to the egg mixture.
Pour the egg mixture over the croissant pieces.
Gently stir to combine, ensuring the croissants are soaked.
Let it sit for 10 minutes to absorb the liquid.
Bake in the preheated oven for 25-30 minutes, until the top is golden.
Remove from oven and garnish with fresh herbs before serving.