Be sure that you give your butter and cream cheese 1-2 hours to soften before beginning, and then preheat your oven to 350º F.
In a large mixing bowl, cream together the packed light brown sugar and the softened stick of butter until smooth with a hand mixer. Next cream the egg and the vanilla into the bowl until smooth, and then set aside.
In a small mixing bowl, combine all of your dry ingredients by gently stirring with a spoon; flour, baking soda, salt, cinnamon, ginger, and nutmeg. Set aside.
Using the fine setting on a box grater, grate 1 medium-sized zucchini and then, using a cheesecloth, press out as much liquid as you can to the point where the cheesecloth is about to break, then measure out 1 C and set aside.
Next, using a hand mixer, intermittently combine the dry ingredients and the buttermilk into the batter by alternating back and forth between the two.
Using a spatula, fold to combine the grated zucchini into the batter.
On a light colored cookie sheet, measure out 1 Tbsp-sized round balls of batter and bake at 350ºF for 12 minutes or until golden brown. Plan on cooking 3-4 cookie sheets worth.
While the cakes are baking, make the icing by creaming together the butter and the cream cheese until smooth and then intermittently adding the powdered sugar. At the end whip in 2 tsp of vanilla, 1 tsp fresh lemon juice, and a pinch of salt to give the frosting a pop of flavor.
Once the cakes are done cooking, place them on a cooling rack.
Once cool, spread the cream cheese on the bottom side of 1 cake and then sandwich between another cake to make a whoopie pie!