Preheat your oven to 425°F (220°C). In a greased pie pan, combine thawed and drained frozen hash browns with melted butter, garlic powder, salt, and black pepper. Press the mixture firmly into the bottom and up the sides of the pan. Freeze the crust for 15 minutes to help retain its shape, then bake for 20-25 minutes until golden brown and crispy.

While the hash brown crust is baking, whisk together the large eggs in a separate bowl until light and frothy. Gradually pour in the milk or half-and-half, stirring continuously until smooth. Add the crumbled bacon, shredded cheddar cheese, and optional green onions, seasoning with salt and black pepper to taste.

Once the crust is out of the oven and slightly cooled, carefully pour the egg and filling mixture into the crispy hash brown crust. Lower the oven temperature to 350°F (175°C) and bake for 30-35 minutes until the filling is set and the top is lightly golden.

Remove the quiche from the oven and let it rest for about 10 minutes before slicing. This allows the filling to set, making it easier to serve.