Pat the thawed hash browns thoroughly with paper towels or a clean kitchen towel to remove excess moisture—this is crucial for achieving a crispy crust rather than a soggy one. In a medium bowl, toss the dried hash browns with melted butter until evenly coated. Press the buttered hash browns firmly into a 9-inch pie plate, creating an even layer along the bottom and sides. I like to use the bottom of a measuring cup to pack it down solidly, which helps it hold together during baking.

Bake the hash brown crust at 450°F for 20-25 minutes until golden brown and crispy. You want the edges to be noticeably darker and the crust to feel firm when you gently press it. While the crust is baking, you can prepare the filling ingredients. Remove the crust from the oven and reduce the temperature to 350°F, then let the crust cool for a minute or two while you finish the filling.

In a medium bowl, whisk together the room temperature eggs and half and half until well combined and slightly frothy. Stir in the sharp cheddar cheese and diced ham, distributing them evenly throughout the mixture. Gently fold in the sliced green onions just before pouring—I add them at the end to keep their bright color and fresh flavor intact rather than letting them cook down too much.

Pour the egg filling from Step 3 into the prebaked hash brown crust from Step 2, filling it until just below the rim of the pie plate. Bake at 350°F for 30 minutes or until the top is golden brown and puffed, and a knife inserted in the center comes out clean. The quiche will continue to set slightly as it cools, so don't overbake it or it will become rubbery.