Preheat the oven to 375 degrees. Grease and flour an 8-inch cake pan.
In the bowl of your electric mixer, beat the almond paste with the sugar until well blended. (Depending upon the temperature of the almond paste, this may take a while)
Beat in the butter and then the egg. In a small bowl, whisk the cocoa powder with the whole-wheat pastry flour. Add the dry ingredients to the batter alternately with the milk. Blend until well incorporated.
Spoon the batter into the prepared pan and bake for 20 -22 minutes, until a toothpick comes out clean. Let cool in the pan for 10 minutes. Transfer to a rack and cool completely.
Serve dusted with powdered sugar, a dollop of whipped cream, or coconut ice cream.