Heat the oven to 350 degrees. Grease a 13x9-inch baking dish or spray with cooking spray.
Mix the hashbrowns with the ham, bell pepper, and 2 cups cheese in a medium bowl.
In another medium bowl, whisk together the eggs, 1 cup of sour cream, milk, oregano, salt, chili powder, and onion powder.
Combine the hashbrown mixture with the egg mixture; pour into the baking dish. Bake for 35 minutes.
Remove the casserole from the oven and sprinkle with the remaining cheese. Return the casserole to the oven and bake for 15 to 20 minutes or until the hashbrowns are tender and knife inserted in the center comes out clean.
Top each slice of casserole with servings with Pico de Gallo and a dollop of sour cream.