Preheat the oven to 180°C. Grease a medium Bundt tin or silicone mould thoroughly.
Cream the butter and sugar together until pale and fluffy.
Beat in the eggs, one at a time, mixing well after each addition.
Purée the mango flesh in a food processor or blender until smooth, then stir it into the egg mixture.
In a separate bowl, mix together the flour, baking powder and bicarbonate of soda.
Gently fold the dry ingredients into the wet mixture, followed by the grated carrots and chopped nuts, if using.
Spoon the batter evenly into the prepared tin or mould.
Bake for about 45 minutes, or until a skewer inserted into the centre comes out clean.
Leave the cake to cool in the tin for 10 minutes, then carefully turn out onto a wire rack to cool completely.
Decorate as you wish for the occasion, or simply dust with icing sugar before serving.