Set oven rack to the middle and preheat to 350°F (176°C). Grease two 8-inch round cake pans. Set a parchment round in the bottom of each pan.
Set the dates in a bowl and cover with hot coffee and hot milk. Cover and let soak for 10 minutes. Add to a food processor and pulse until smooth.
In a small bowl combine flour, cocoa, cayenne, baking soda, and salt. Stir well.
Add the butter, sugar, and brown sugar to the bowl of an electric mixer. Beat on medium-low until light and airy, about 4 minutes. Add eggs one at a time, beating each until incorporated. Add vanilla and beat until well mixed.
With the mixer on low, add the dry ingredients 1/2 cup at a time, mixing after each addition just until incorporated. Add the dates to the batter and gently fold with a spatula, stopping as soon as the batter is uniform in texture.
Scoop the batter into the prepared baking pans and bake for 30-40 minutes, or until the sides pull away from the pans. Allow to cool for 20 minutes in the pans, then carefully turn out onto a cooling rack to cool completely.
Wrap cakes in plastic wrap and set them in the freezer for 4 hours.
Remove cakes from freezer. Work quickly to slice each cake horizontally into two layers of equal thickness. You should have four layers total.
Set one layer of cake on a cake round, and place the remaining three layers of cake back in the freezer. The layers are much easier to handle when frozen. Pull them out as you need them, one at a time.
Use a large, round piping tip to pipe chocolate buttercream on top of the cake, following the rounded edge of the cake. Scoop 1/2 cup of chocolate buttercream into the circle and smooth flat with an offset spatula. Sprinkle evenly with 1 tablespoon of espresso powder and set the next layer on top.
Repeat with the second and third layers of cake. When you place the fourth layer on top, do not frost the top.
Spread a thin crumb coat on the sides of the cake with the remaining buttercream and set the cake to chill in the refrigerator for 30 minutes.
Gently warm the ganache over a double-boiler just to the point that it flows well but is not too thin or watery. Set the chilled cake on a cooling rack placed into a baking sheet and carefully pour the ganache over the entire cake, coating the top and sides in one smooth layer.
Set the cake in the refrigerator to chill for 20 minutes to set the ganache. Serve at room temperature.
Special Equipment: two 8-inch round cake pans, food processor, parchment paper cut to fit pans.Nutritional analysis based on 12 portions and does not include buttercream frosting or ganache.