1. Preheat the oven to 180°C. Line two round cake pans or a longer loaf tin with baking paper.
2. Add all dry ingredients to a large mixing bowl. Mix until combined and there are no lumps. Set aside.
3. Add the pistachios to a food processor and blitz until it forms medium to fine crumbs. Add the avocado, milk, oil, lime juice/zest, and vanilla. Blitz until there are no more chunks of avocado.
The mixture may be lumpy from the pistachios.
4. Pour the pistachio mixture into the mixing bowl with the flour. Mix gently until combined. The batter needs to be quite thick (otherwise the cake will not bake through).
5. Pour or scoop the cake batter into your cake tin.
6. Bake the cake for 40 minutes.  Allow the cake to rest in the tin for a few minutes. Remove it from the tin and allow it to cool on a wire rack. Let it cool before frosting. Place in the fridge if needed.
7. Cream the vegan butter/margarine, sift in the icing sugar, and then cream until smooth, fold in the matcha powder, and lime juice, and cream until smooth.
8. Frost the cakes and add pistachios on top of the cake, let it chill slightly to set if needed, serve
and enjoy!