Cake: Mix flour and baking soda together. Dissolve coffee in water. Beat sugar, eggs, and vanilla together. Incorporate mayonnaise into the chocolate, add to the mixture. Add dry ingredients, alternating with coffee. Pour into two 9-inch greased and floured round pans. Bake at 350 F. Remove from the oven and let cool in pans for 10 minutes before unmolding. Let cool completely. Cut each cake into 4 discs.

Glaze: Melt chocolate, milk, and coffee in a double boiler. Beat until smooth. Cool. Beat butter and sugar until light. Add egg and beat for 1 minute at high speed. Incorporate chocolate mixture into the butter mixture and mix well. Use about 3/4 cup per cake layer.