Sift your flours in a bowl. Mix in your baking powder and salt. In another bowl, mix the sugar with the lemon zest.
In another bowl, whip the butter and sugar mixture. Mix in your eggs, egg whites and lemon extract. Whisk together the buttermilk and lemon juice. (Add yellow food coloring if you want the yellow to be brighter).
Alternate mixing the flour and buttermilk mixtures until they are combined. Pour the batter into your cupcake liners and bake for about 20 minutes.
While you wait, you can prepare the frosting. Mix the sugar and the butter and beat for about three minutes.
Add the whipping cream and the drink mix and beat the mixture together for about one minute. Once the cupcakes have cooled, you can ice them and add lemon slices for embellishment.