Preheat oven to 425 degrees. Spray a 9x13-inch casserole dish with nonstick spray.
Place potatoes, onion and red pepper in prepared dish and press flat.
Bake for 20 minutes.
Reduce oven heat to 350 degrees.
Top potatoes with ham then sprinkle cheese on top.
In a medium bowl, whisk eggs and combine with milk, salt & pepper.
Pour over potato-ham mixture.
Place in oven and bake 1 hour.
Garnish with green onions.