Preheat oven to 350°F and place rack in center of oven.
Spray non-stick spray in baking pans or dish. Batter makes enough for either 3 - 8" rounds, 3 - 9" rounds, a 13 x 9" baking dish, 36 cupcakes, or 2 - 8" squares.
In medium bowl, blend flour, baking soda, and salt. Set aside.
In large mixing bowl, beat butter and sugar until light and fluffy.
Beat in 1 egg yolk at a time. Stir in chocolate.
Starting with flour mixture, alternate flour and buttermilk in batches. (Four parts flour mixture to 3 parts buttermilk.) Batter will be thick.
In separate clean bowl, beat egg whites with clean beaters on low for about a minute. Increase speed to medium for about 5 - 10 minutes as whites begin to stiffen up.
Fold egg whites into cake batter in 2 batches. Divide evenly into prepared pans.
Bake 30 - 35 min. for 9" rounds, 35 - 40 min. for 8" rounds, 45 - 50 min. for 13 x 9" dish, 25 - 30 min. for cupcakes, and 45 - 50 min. for 8" squares.
Allow cake to cool in pans for 10 minutes, then remove from pans to wire rack. Cool completely before frosting.
Typically served with coconut pecan frosting. For 3-layered cake, you may need extra frosting. Enjoy!