Follow these simple steps to create your delicious Cheesy Sausage-and-Croissant Casserole:

1. Preheat the Oven: Preheat your oven to 350°F (175°C).
2. Cook the Sausage: In a skillet over medium heat, cook the crumbled sausage until browned and fully cooked. Drain any excess grease and set aside.
3. Prepare the Croissants: In a large mixing bowl, combine the croissant pieces and cooked sausage. Toss gently to mix.
4. Add Cheese: Stir in the shredded cheddar and mozzarella cheese, ensuring the croissant pieces are well-coated.
5. Mix the Eggs: In another bowl, whisk together the eggs, milk, garlic powder, onion powder, salt, black pepper, and crushed red pepper flakes (if using).
6. Combine Mixtures: Pour the egg mixture over the croissant and sausage mixture. Gently stir until everything is evenly coated.
7. Transfer to Baking Dish: Grease a 9×13-inch baking dish and pour the mixture into it, spreading it evenly.
8. Bake: Place the dish in the preheated oven and bake for 30-35 minutes, or until the top is golden brown and the casserole is set.
9. Cool and Garnish: Remove from the oven and allow it to cool for a few minutes. Garnish with fresh parsley before serving.

These simple steps will guide you in creating a delicious Cheesy Sausage-and-Croissant Casserole that will impress your family and friends!