Preheat oven to 350 Degrees F.
In a saucepan over low heat melt chocolate with water. Cool.
In large mixing bowl, cream butter and sugar until smooth.
Add egg yolks one at a time making sure fully incorporated before adding next egg.
Add chocolate mixture and vanilla to egg/sugar mixture mixing well.
In another mixing bowl, combine flour, baking soda and salt.
Add flour mixture alternately with buttermilk to the mixing bowl with the chocolate mixture.
In another mixing bowl, beat egg whites until stiff peaks form; fold into chocolate batter.
Spray (2) 9-inch baking pans with cooking spray. Divide batter evenly between the two pans.
Bake for 28-32 minutes or until a toothpick comes out clean from the center.
Cool in pan for 10 minutes and then remove onto cooling rack and cool completely.