This is a particularly useful recipe because it can be cooked as one large cake (use a 9-inch-diameter springform cake tin and cook for about 1 hour) or divided in half and cooked as a loaf and 12 cupcakes.
For the Cake:
Preheat oven to 325°F. Grease the sides of a 5-cup-capacity loaf tin and line the base with baking paper. Line a 12-hole muffin tin with paper liners.
Grate the zucchini onto a clean tea towel (you should have about 3 cups), pull up the sides, twist and squeeze tightly over a sink or bowl to remove liquid.
Beat oil and sugar in a food processor, mixer or large bowl. Beat in eggs, then stir or pulse in flour, cocoa, spices, vanilla and squeezed zucchini.
Dissolve baking soda in orange juice and fold or pulse in very briefly so as not to over-work the gluten (this will make the cake tough). Pour half into the prepared loaf tin and divide the rest between the cupcake cases. Bake until the tops spring back when pressed and a skewer inserted into the center comes out clean (20 minutes for cupcakes and about 45 minutes for the loaf). Allow to cool a little before turning out onto a rack. Store in a sealed container in a cool place for up to a week.
For the Cream Cheese Icing:
Blend butter and cream cheese in a mixing bowl or food processor until smooth. Beat in confectioner's sugar, salt and lemon juice, adding a little more confectioner's sugar or water if necessary to achieve a spreadable consistency. Spread over loaf and cupcakes.