Pre-heat the oven to 180 Celsius / 350 Fahrenheit.
Peel and then grate 3-4 small zucchini. Using a kitchen cloth, squeeze as much liquid out as possible. You should end up with 1 ½ cup or 230g shredded zucchini.
Whisk the eggs with an electric mixer or in a food processor until pale, frothy and doubled in size. Add the butter and vanilla and blend.
Add the zucchini and blend until combined.
Mix all dry ingredients in a separate bowl – almond flour, coconut flour, baking powder, erythritol, cinnamon and nutmeg – making sure there are no lumps. Then add to the batter and blend until combined.
Stir in half the nuts.
Line a loaf tin with parchment paper and fill in the batter. Top with the remaining nuts.
Bake for about 50 minutes or until a toothpick/knife inserted comes out clean. If the cake gets too brown, cover the top loosely with aluminium paper.
Let cool completely before slicing.