Preheat oven to 350 degrees. Coat a 9 x 9-inch baking pan with cooking spray.
In a bowl, cook onions and red peppers in microwave for 3 minutes. Drain liquid.
In a large bowl, add cooked onions and peppers, ham, yogurt, cottage cheese, and milk. Mix well. Stir in eggs, egg whites, ¼ teaspoon seasoning salt or salt and pepper. Mix well.
Pour mixture into baking pan. Spread evenly. Cover the top evenly with frozen hash browns. Make sure to break up the chunks of frozen potatoes. Spray the top generously with cooking spray. Sprinkle top with ½ teaspoon seasoning salt or salt.
Cover casserole with foil and bake in oven for 30 minutes. Remove cover and bake for an additional 30 minutes. To crisp hash browns, place under broiler for 2-3 minutes until golden brown. Be sure to keep an eye on it while broiling to not burn.
Remove from oven and let sit for 10 minutes to set. Cut into 6 slices.
This casserole can be reheated and it freezes great! It can be easily doubled and made in a 13 x 9-inch baking dish.