Preheat oven to 350°. Grease a 9 inch round cake pan and line with a round of wax or parchment paper. I like to use a 9 inch springform.
Combine dates, cocoa, boiling water, and 1 teaspoon coffee granules or instant espresso powder; let stand 20 minutes.
Reserve 10 of the walnut halves or about 2 T. of the walnut pieces. Combine remaining walnuts, flour and salt in bowl of food processor and process until fine. Pour flour mixture into a mixing bowl.
Process the bread into crumbs, then add to the mixing bowl with the walnut/flour mixture.
Place date mixture, 1/3 cup of the granulated sugar, oil, vanilla, and the one whole egg in food processor, and process until smooth, scraping the sides of bowl once. Pour the date mixture into bowl with flour mixture.
In a clean mixing bowl beat egg whites with a mixer at high speed until soft peaks form. Gradually add the remaining 1/3 cup granulated sugar, 1 tablespoon at a time, beating until stiff peaks form. Gently stir one-fourth of the egg white mixture into batter; Fold in the remaining egg white mixture.
Spread batter into prepared pan. Bake at 350° for 25 minutes or until cake springs back when lightly touched. Cool in pan for 10 minutes on a wire rack, and remove from pan. Remove the parchment. Cool completely on wire rack.
To prepare glaze, combine 1/3 cup cocoa and the next 4 ingredients (cocoa through 1 teaspoon coffee granules), stirring until smooth. Stir in 1/2 teaspoon vanilla. Cover and chill for about an hour. Gradually add powdered sugar to the cocoa mixture, beating with a mixer at medium speed until smooth and thick.
Place cake layer on a plate. Spread the glaze evenly over top and sides of cake and arrange walnut halves or sprinkle walnuts across top.