To prepare a violet and rose white chocolate fairy cakes recipe, first you need to prepare your ingredients. First, you will need your flour, sugar, baking powder, cocoa, and vanilla extract. Then, add your dry ingredients to the wet ingredients and mix until everything is evenly combined. Now, it's time for the frosting. You want to make sure that your frosting isn't too thick or too runny, as this will cause the cake to fall apart when you cut it into squares. Finally, pour your batter into your prepared pan and bake it in the oven for 20 to 25 minutes, or until the top is golden brown. Allow the cakes to cool completely before removing them from the pan.