Preheat oven to 170°C fan.
Grate the carrots. Finely chop the walnuts and the pineapple.
In a large bowl, whisk the eggs at high speed, add the sugar and continue beating until pale and fluffy. Keep the whisk on at high speed, and add the oil in a steady stream.
In a separate bowl, mix the flour, dessicated coconut, the cinnamon, baking powder and salt, then fold into the egg mix. Once mixed, gently incorporate the grated carrot, the pineapple and the walnuts.
Line a muffin tin with 12 cupcake cases.
Transfer the mixture into the muffin tin and bake for 25-30 minutes, or until a skewer comes out clean.
Prepare the frosting. In a bowl, cream the butter and icing sugar together until smooth. Add the cream cheese and cream until smooth. Put in the fridge to set.
Once your cupcakes are done, put them on a wire rack and leave to cool. Once cool, spread the frosting generously over the top.
Cut the marshmallows diagonally in halves and dip each marshmallow, cut-side down, into the sprinkles. Stick onto the frosting to create little ears, then decorate with a Smartie to create a nose.
Store the cupcakes in the fridge for up to 3 days.