Preheat oven to 350 degrees Grease and flour three 9-inch cake pans of butter. Add eggs one at a time, beating well after each addition. Mix soda and salt into buttermilk until foamy. Add alternately with flour. Add 3 teaspoons flavoring. Pour into prepared pans and bake until done, 20 to 25 minutes. teaspoons flavoring. Add nuts. Spread on cooled cake.