Old-fashioned Buttermilk Fudge

Description
From my Aunt Minnie's Collection. Dated 1942. Another tried and true recipe that I take to my yearly cookie exchange in December.
 * Contributed by Cat's Recipes Y-Group

Ingredients

 * 1 cup buttermilk
 * 2 cups granulated sugar
 * 1 teaspoon baking soda
 * ½ stick unsalted butter
 * 1 cup pecans, chopped

Directions

 * 1) Cook in kettle until soft ball forms in cold water.
 * 2) Add butter and let get cold before stirring.
 * 3) Add chopped nuts and beat until creamy.
 * 4) Drop with teaspoon on marble slab.