Preheat oven to 425 degrees.
Thaw hash browns and then use a paper towel to squeeze moisture out of the hash browns.
Place hash browns in a bowl and add 1/4 tsp salt, 1/4 tsp pepper, and garlic powder. Stir.
Press the hash browns onto the bottom and sides of 9 inch pie plate. Using the back of a measuring cup to press down and flatten the hash browns.
Drizzle melted butter over hash browns and bake for 25 minutes or until slightly browned.
In a bowl, combine ham, green onion, and cheese.
In a separate bowl, combine eggs, milk,1/4 tsp salt, and 1/4 tsp pepper.
Once crust is ready, spread ham mixture on the bottom and then cover with egg mixture.
Reduce oven to 350 degrees. Bake casserole for 25 minutes or until cooked through.