Prepare a 25 cm cake tin by lining with baking paper.
Set oven to 170 degree Celsius.
Beat the butter with the sugars until light and creamy. Do not hurry this step.
Add the eggs one at a time with a spoonful of the measured flour to prevent the mixture from curdling. Add the vanilla and yoghurt and mix well.
Sift the dry ingredients together then mix until partly combined with the egg mixture. Add the zucchini. Do not overmix.
Turn into prepared tin. Bake at 170 for 45 minutes, or until a skewer comes out clean when poked into the cake. Cool in tin for 10-15 minutes, then turn out onto cake rack. When cold, icing with a cream cheese icing.
Chocolate Cream Cheese Icing: Beat together 250 grams cream cheese, 1 T cocoa, ½ teaspoon vanilla essence, 1 T softened butter and enough icing sugar to get spreadable consistency (approx. ½ - ¾ cup).