Preheat the oven to 175 °C. Grease a square tin (approx. 20×25 cm) or small springform tin and dust with flour.
Mix flour, almonds, sugar, baking powder, baking soda and cinnamon in a bowl. Whisk together the oil, milk of choice and vinegar in another bowl.
Mix the dry and wet ingredients together with the grated carrots thoroughly, but not for too long.
Pour the batter into the dish, smooth it out and bake for 35-40 minutes. To prevent burning, cover towards the end of the baking time if the cake gets too dark.
Leave the carrot cake to cool. Meanwhile, prepare the frosting with icing sugar, cream cheese and lemon zest. Cool again briefly.
Spread the frosting on the cooled cake. Cut into pieces and decorate with marzipan carrots, chopped pistachios or nuts as desired.
The cake should be well chilled when serving and can be stored in the refrigerator.