Clean, wash and roughly grate the zucchini. Coarsely chop the chocolate and cashew nuts. Melt the fat in a small pot. Remove from the heat and let it cool down a little. In the meantime mix flour, sugar, cocoa, baking powder and vanilla essence in a bowl.
Place the eggs in a mixing bowl and whisk until creamy. Let the fat run in and stir in. Mix in the flour mixture well with a wooden spoon. Then mix in the zucchini, chocolate and cashew nuts well.
Place the dough in a well greased, flour-spread rectangular baking tin (27 x 18 cm, type fat pan), smooth it down. Bake in a preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for 30-35 minutes.
Remove from the oven, place on a cake rack and allow to cool.