Preheat oven to 350°F. Grease and flour a 9 by 13 inch pan. Sift flour, baking soda and salt. Set aside. In a large bowl, cream 2/3 cup butter and white sugar until light and fluffy. Add 2 eggs and 2 squares of melted chocolate. Add flour mixture alternately with beer, buttermilk and cherry juice. Mix until smooth, then fold in cherries and chopped nuts. Pour batter into a 9 by 13 inch pan. Bake at 350°F for 45 to 60 minutes, or until a toothpick inserted into the center of cake comes out clean. Frosting In a large bowl, combine 2/3 cup butter, 1 egg, 4 squares melted chocolate, confectioners sugar and milk. Beat until smooth. Spread on top of cooled cake.