1/2 cup butter, softened
1/2 cup shortening
1/2 cup white sugar
2 eggs
1 (12 ounce) package frozen hash brown potatoes
1/2 teaspoon salt
1/4 teaspoon ground black pepper
Preheat oven to 350 degrees F (175 degrees C). Lightly grease a 9x13 inch baking dish.
In a large bowl, cream together the butter, shortening and sugar until smooth and creamy. Beat in the eggs one at a time, then stir in the mashed potatoes. Fold in the salt and pepper. Pour batter into prepared dish, leaving approximately 1/3 inch hanging over edge of oven.
Bake in preheated oven for between 200 and 225 minutes, or until knife inserted in center comes out clean.