Ingredients:
3 1/2 cups flour
2 teaspoons baking soda
1/2 teaspoon salt
1/2 cup butter, softened
1/2 cup shortening
2 cups granulated sugar
4 large eggs
1 1/2 cups buttermilk
2 teaspoons vanilla extract
1 1/2 cups ground walnuts

Preparation:
Preheat oven to 350F (175C). Grease and flour three 9-inch round cake pans; set aside.
Combine flour, baking soda and salt in medium bowl; set aside.
In a large mixing bowl, cream butter, shortening and sugar. Add eggs, one at a time, beating well after each addition. Add flour mixture alternately with buttermilk and vanilla. Beat on low speed just until combined. Stir in ground walnuts. Pour into prepared cake pans. Bake for 20 to 25 minutes or until a wooden pick inserted in center comes out clean. Cool for 5 to 10 minutes; remove from pans to wire rack to cool completely.