To prepare cake: Preheat oven to 350 degrees F. Coat a 9-inch round cake pan with cooking spray. Line the bottom with parchment or wax paper.Advertisement
Combine dates, cocoa and instant coffee in a small bowl. Add boiling water and stir until the cocoa has dissolved. Cover and let stand until the dates have softened and the mixture has cooled to room temperature, about 20 minutes.
Meanwhile, spread hazelnuts in a shallow baking dish and bake until fragrant and lightly toasted, 5 to 10 minutes. Transfer to a plate and let cool.
Grind bread into fine crumbs in a food processor. Measure to make sure you have 1/2 cup. Transfer to a large bowl. (No need to wash the workbowl between steps.)
Place 1/2 cup of the hazelnuts in the food processor. Add flour and salt; process until the nuts are finely ground. Transfer to the bowl with the breadcrumbs.
Scrape the cooled date mixture into the food processor. Add 1/3 cup sugar, oil, vanilla and whole egg; process until smooth, stopping several times to scrape down the sides of the workbowl. Scrape the mixture into the bowl with the breadcrumbs and nuts. Mix gently with a rubber spatula.
Beat egg whites with an electric mixer in a clean large mixing bowl until soft peaks form. Gradually add remaining 1/3 cup sugar, beating until stiff, glossy peaks form. Add one-fourth of the beaten whites to the batter and whisk until blended. Fold in the remaining whites with a rubber spatula just until blended. Scrape the batter into the prepared pan, spreading evenly.
Bake the cake until the top springs back when touched lightly, 25 to 35 minutes. Let cool in the pan on a wire rack for 5 minutes. Coat the rack with cooking spray and invert the cake onto it to cool completely.
Meanwhile, to prepare glaze: Combine cocoa, chocolate, corn syrup and instant coffee in a medium bowl. Add boiling water and stir with a wooden spoon until the chocolate has melted and the mixture is smooth. Stir in vanilla. Gradually add confectioners' sugar (to the chocolate mixture), beating with an electric mixer, slowly at first, then gradually increasing speed, until the glaze is smooth and thickened. (The mixture may seem lumpy at first, but it will smooth out.) Cover with plastic wrap and let sit at room temperature until the mixture is set, about 30 minutes.
To finish the cake, place it bottom-side up on a serving plate. Place several strips of wax paper under the bottom edge to protect the plate from drips. Spoon on glaze and spread it evenly over the top and sides of the cake with an icing spatula or knife. Arrange the remaining 2 tablespoons hazelnuts around the top outside edge. Discard the wax paper before serving.
Make Ahead Tip: Prepare through step 8. The cake will keep, well wrapped, at room temperature for up to 1 day or in the freezer for up to 3 months.
Equipment: 9-inch round cake pan
Storage smarts: For long-term freezer storage, wrap your food in a layer of plastic wrap followed by a layer of foil. The plastic will help prevent freezer burn while the foil will help keep off-odors from seeping into the food.
2 other carbohydrate, 1 1/2 fat