Preheat the oven to 350°F (175°C). Grease a 9×13-inch casserole dish and set aside.
In a large skillet over medium-high heat, cook the sausage until fully browned, breaking it into crumbles as it cooks. Remove the sausage from the skillet and set aside.
In the same skillet, heat the frozen hashbrowns for 8–10 minutes, stirring occasionally, until lightly browned and mostly thawed.
Spread the hashbrowns evenly in the bottom of the prepared casserole dish.
Layer the cooked sausage over the hashbrowns, then sprinkle the shredded cheddar cheese evenly on top. Add the drained green chilis over the cheese layer.
In a large mixing bowl, whisk together the eggs, milk, garlic powder, onion powder, salt, and pepper until smooth and well combined.
Pour the egg mixture evenly over the layered casserole, making sure it covers all ingredients.
Bake uncovered for 35–40 minutes, or until the eggs are fully set and the top is slightly golden.
Allow the casserole to cool for a few minutes before slicing and serving.
Enjoy!