Preheat the oven to 180°C and grease six 10x5cm moulds or a muffin tin.
Whisk eggs, sugar, salt, and oil in a large bowl.
Fold in carrots, walnuts, flour, baking powder, bicarbonate of soda, and cinnamon.
Spoon batter into moulds and bake for 25 minutes.
Combine cream cheese, sugar, pistachio paste, and green colouring to make the topping.
Cool cakes completely before spreading the pistachio topping over them.
Mould marzipan mixed with food colouring into mini carrot shapes.
Place marzipan carrots on cakes and dust with cocoa powder.
Sprinkle cocoa nibs along the top to resemble soil.