Preheat the oven to 350°F (175°C). Grease a 9x13-inch baking dish with cooking spray or butter.

In a large mixing bowl, whisk together the eggs, whole milk, garlic powder, salt, black pepper, and paprika until well combined.

Layer the torn croissant pieces evenly in the prepared baking dish. Sprinkle the cooked sausage, diced bell pepper, and onion over the croissants.

Pour the egg mixture over the croissant and sausage layers, ensuring everything is evenly soaked. Press down gently with a spatula to help the croissants absorb the liquid.

Sprinkle the shredded cheddar cheese evenly on top.

Cover the baking dish with plastic wrap and refrigerate for at least 2 hours, or preferably overnight, to allow the flavors to meld and the croissants to soak up the egg mixture.

In the morning, remove the casserole from the refrigerator and let it sit at room temperature for about 15 minutes.

Bake in the preheated oven for 35-40 minutes, or until the casserole is puffed and golden brown. A knife inserted in the center should come out clean.

Let it cool for a few minutes before slicing. Garnish with chopped parsley before serving.