1. Heat oven to 350 degrees F. Line 24 regular size muffin cups with paper liners.
2. Whisk flour, cocoa, salt and soda in large bowl. Combine buttermilk and water in small bowl. Beat butter in another large bowl with mixer on medium high speed until fluffy.
Add sugar and beat 3 minutes. Add eggs, one at at time, beating well after each addition. Beat in vanilla. Alternately add flour and buttermilk in 3 batches, beating just until blended. Spoon into cups, 2/3 full. Bake 20 - 22 minutes or until toothpick comes out clean. Cool in pan on wire rack 5 minutes and then remove to a rack and cool completely.
Frosting: Heat chocolate and cream in medium saucepan over low heat, stirring until chocolate melts and mix is smooth.
Add butter and whisk until blended and melted. Cool to room temperature in a medium mixing bowl. Cover and refrigerate 15 minutes. Beat with mixer on med high speed about 3 minutes or until thick enough to spread. Frost cupcakes. Refrigerate 30 minutes until frosting is set.