Cake: Heat oven to 350 degrees F. Grease and flour a 9-inch square pan.
Stir together baking soda and boiling water in a medium-size bowl until
baking soda is dissolved. Stir in nuts and dates.
With mixer at low speed, beat together sugar and mayonnaise in large bowl
until well blended. Add chocolate and vanilla extract; beat until well blended.
Add date mixture; beat until blended. Gradually beat in flour until smooth.
Turn into prepared pan.
Bake until wooden pick inserted in center of cake comes out clean, 45 to
Cool cake in pan on rack. Dust with confectioners' sugar and serve with
whipped cream or frost with Fudge Frosting if desired.
Fudge Frosting: Stir together all ingredients in a small bowl until blended.