Preheat your oven to 375°F (190°C). Grease a 9x13-inch baking dish with cooking spray or butter.
In a large mixing bowl, whisk together the eggs, milk, garlic powder, onion powder, black pepper, and salt until well combined.
Add the cooked sausage and 1 cup of shredded cheddar cheese to the egg mixture, stirring gently to combine.
Open the biscuit dough and cut each biscuit into quarters. Gently fold the biscuit pieces into the egg mixture until evenly distributed.
Pour the mixture into the prepared baking dish, spreading it out evenly.
Sprinkle the remaining 1 cup of cheddar cheese over the top.
Bake in the preheated oven for 25-30 minutes, or until the casserole is set in the middle and the top is golden brown.
If using, sprinkle chopped green onions on top before serving. Let it cool for a few minutes before slicing and serving.