Serves: 24 cakes1) Preheat the oven to 180C/Gas 4. Line 24 standard cupcake cups with paper liners. Set aside.
2) In a medium grease-free bowl, beat the egg whites to soft peaks with an electric mixer. Slowly add 65g of the sugar and beat to stiff peaks. Set aside.
3) In a large bowl, sift together the flour, sugars, baking powder and salt. Add the remaining ingredients and beat with the same mixer (no need to wash beaters) until combined, about 1 minute. Fold the egg whites into the batter being careful not to deflate them.
4) Spoon the mixture into each cupcake cup liner, filling a little over half full. Bake for approximately 18 minutes or until a skewer inserted comes out clean.
5) Let the cupcakes cool in the pan for about 5 minutes then remove to a wire rack to cool completely.
For the buttercream:
1) Place the water and sugars in a small saucepan and stir to combine. Bring to the boil over a medium heat and continue to cook for approximately 5 minutes until the sugar is dissolved.
2) Whip the egg whites in a stand mixer (make sure the bowl is grease-free) to stiff peaks. Slowly add the hot sugar syrup to the egg whites and continue beating on a high speed until the bowl is cool to the touch, about 10 to 15 minutes.
3) Add the butter, a piece at a time, mixing completely before adding the next piece of butter. Repeat until all the butter has been used. Add the icing sugar and mix to combine. Add the orange liqueur and 2 tsp of zest and mix to combine.
4) The icing should now be smooth and creamy. Generously ice the cupcakes with a piping bag or spatula and top with coarsely grated orange zest. Serve immediately.