Press hash browns onto the bottom and sides of a 9 inch pie dish. Drizzle with melted butter, and sprinkle with seasoning salt. Bake in preheated oven for 20 minutes, or until beginning to brown.
In a small bowl, combine ham, onion and shredded cheese. In a separate bowl, whisk together eggs, milk, salt, pepper, and a little seasoning salt. When crust is ready, spread ham mixture on the bottom, then cover with egg mixture.
Reduce oven temperature to 350 degrees F (175 degrees C.) Bake in preheated oven for 20 to 25 minutes, or until filling is puffed and golden brown.