Make the cake: Adjust oven rack to middle position and preheat to 350 degrees F. Line bottoms of two 8-inch cake pans with parchment paper and spray with pan spray. Sift fl our, cocoa, baking soda and salt into a large bowl. Whisk sugar, sour cream, oil, eggs, vanilla and espresso together until smooth. Whisk wet ingredients into dry until smooth. Divide into pans and bake until toothpick inserted in center comes out with moist crumbs (about 25 minutes). Let cakes cool in pans about 15 minutes, then remove to cool completely on wire racks.
Make the coconut-pecan filling: Mix yolks, sugar and salt in a medium bowl. Beat in the softened butter (should be quite soft but still cool) and then gradually beat in the cream. Pour into a medium nonreactive saucepan and cook over low heat, stirring constantly, until the mixture is puffy and just begins to thicken (180 degrees on an instant-read thermometer) for about 15-20 minutes. Pour into a bowl and cool to room temperature.
Stir in toasted pecans and coconut. (For an extra smooth filling, after filling cools slightly, I blend for a few seconds in the blender before adding pecans and coconut).
Assemble: Using a long serrated knife, cut the cakes in half horizontally so that each cake forms 2 layers. Place one of the cake bottoms on a serving plate. Spread with one cup of filling over cake half. Place another cake round over the filling. Repeat this process ending with a final layer of filling on top. Dust lightly with powdered sugar. (If desired, sprinkle extra toasted around). Cut cake and enjoy!
Recipe courtesy of Susan Guthrie