Preheat the oven to 170 C / Gas 3. Line a 12 hole muffin tin with paper cases.
Place the eggs, brown sugar and sunflower oil in a bowl and beat until it's all well combined. Slowly mix in the flour, bicarbonate of soda, cinnamon, ginger, salt and vanilla paste until its well combined and really smooth. Fold in the carrots and walnuts. Spoon mixture evenly into the cupcake cases filling only to half way to allow for a good rise.
Bake in the preheated oven for 20 to 25 minutes until risen and golden brown and a skewer inserted into the centre comes out clean. Remove from the oven and allow to cool completely on a cooling rack, about 1 hour.
For the cream cheese icing:
In a bowl combine the margarine and cream cheese and beat together until well combined. Slowly add the icing sugar until its all incorporated. Place in a piping bag and pipe onto the cupcakes.
Cut the walnuts into quarters and place one on top of each of the cream cheese icing to decorate. Serve and enjoy!