Combine the fed starter, milk and spelt flour in a mixing bowl. Cover and let rest at room temperature for 8 hours. If not ready to bake the cake, transfer this mixture to the refrigerator until ready to finish the cake, but allow it to come back to room temperature before proceeding.
Preheat the oven to 350 degrees. Grease a 9x13 cake pan or 2 – 8” or 9” square or round cake pans with coconut oil and set aside.
In a separate mixing bowl, combine the evaporated cane juice, coconut oil, vanilla, salt, baking soda, cocoa powder, and Teeccino. Beat. Add the eggs and beat well.
Combine the sourdough mixture with the chocolate mixture. Mix gently until smooth. Pour into prepared pan(s).
Bake for 30 to 45 minutes (mine baked for about 35 minutes), until a toothpick inserted in the center comes out clean. Remove from the oven and set on a rack to cool.
Make the Frosting:
Combine all the frosting ingredients in a blender or food processor and blend until smooth. Chill.
Assemble the cake:
If cakes are in a square or round pan, tip them onto a platter. Spread the frosting between the layers and on top.
If cake is in one rectangular pan, spread the frosting on top. Serve!