1. Preheat the oven to 180 °C. Line a muffin pan with 18 paper cups.
2. Add the mint leaves to the hot milk and leave to steep for 12 to 15 minutes. Remove the mint; leave the milk to cool slightly.
3. Sift together the flour, baking powder, bicarbonate of soda and salt.
4. In the bowl of an electric mixer, with a paddle attachment beat the butter until creamy. Add the sugar and continue beating on medium speed for approximately 5 minutes, until the mixture becomes light and fluffy.
5. Add the eggs, one at a time, then mix in the lime zest, vanilla essence and rum. On a low speed, add the flour mixture and milk alternately, ending with the flour.
6. Spoon the mixture into the muffin cups until half-full. Bake for 20 minutes. Allow to cool before piping on meringue icing. Decorate with slices of lime and mint leaves.
1. In the heatproof bowl of an electric mixer, combine the egg whites, sugar and salt.
2. Set the bowl over a pan of simmering water and hand-whisk continuously for 3-5 minutes until the sugar has dissolved and the mixture is hot to touch.
3. Attach the bowl to the electric mixer with the whisk attachment, and beat until the mixture has cooled down and stiff peaks form. Use immediately.