3 tablespoons butter
1/2 cup shortening
1/2 cup white sugar
3 eggs
2 teaspoons vanilla extract
4 1/4 cups all-purpose flour
1/2 teaspoon baking powder
1/4 teaspoon salt
1/4 cup milk
1/2 cup chopped walnuts (optional)
Preheat oven to 350 degrees F (175 degrees C). Grease an 11x17-inch baking dish.
In a large bowl, cream together the shortening and 1/2 cup of white sugar until light and fluffy. Blend in the eggs, 1 teaspoon of vanilla, and the flour. Stir in the baking powder, salt, 1/2 cup milk and 1/2 cup of the walnuts. Pour into prepared pan.
Bake in the preheated oven for 40 to 45 minutes, or until a toothpick inserted into the center comes out clean. Let cool 10 minutes before frosting.