Cream the butter and sugar together, then add the lime zest.
Add the eggs one at a time, and mix well after each addition.
Fold in the flour and baking powder a half at a time, and after each half stir in half the yoghurt.
Stir in the fresh mango.
Grease and line your slow cooker pot with either baking paper or a large cake tin liner.
Pour the cake batter into the prepared pot. Sprinkle on some more lime zest.
Turn the slow cooker onto high and cook for around 1.5 to 2.5 hours or until a skewer comes out clean. Check regularly without lifting the lid to watch out for burning.
Remove the cake from the slow cooker pot and allow to cool completely.
Mix together the icing ingredients and decorate the cake. Top with some fresh lime zest.