Preheat the oven to 400°F (200°C). Lightly coat a 9-inch pie plate or quiche pan with non-stick spray or grease with butter.
Thoroughly squeeze the moisture from the thawed shredded potatoes using paper towels or a clean kitchen cloth.
In a mixing bowl, combine the drained hash browns with melted butter, salt, and black pepper. Mix until evenly coated.
Press the hash brown mixture into the prepared pan, pressing firmly along the bottom and sides to form an even crust.
Place the crust in the oven and bake for 20 to 25 minutes, or until the edges turn golden and begin to crisp. Remove from oven and reduce the oven temperature to 375°F (190°C).
In a separate bowl, beat together the eggs, cream (or half-and-half), garlic granules, onion granules, salt, and pepper until the mixture is smooth and fully incorporated.
Fold in the crumbled bacon, shredded cheddar, and chopped green onions, if using.
Carefully pour the egg mixture over the pre-baked hash brown crust, using a spatula to ensure the filling is distributed evenly.
Bake at 375°F (190°C) for 35 to 40 minutes, or until the center is set and a knife inserted in the middle comes out clean. Tent loosely with foil during the final 10 minutes of baking if the top becomes too brown.
Allow the quiche to rest for 10 minutes before cutting into slices, allowing the filling to stabilize for easier serving.