Beat the oil, eggs, sugar and essence with electric mixer until fluffy.
Add the carrots and banana and mix with wooden spoon until incorporated.
Sift the flour, salt, baking soda and spices. Add to the egg mixture and mix until incorporated.
Add spoonsful of batter to your muffin cups, filling them ½ to ¾ full.
Bake for 20 minutes until brown and tester comes out clean.
Combine icing sugar with a little lemon juice at a time to achieve the correct consistency. Pipe or smear cooled down muffins with icing and sprinkle with nuts.