Take a break from baking Chinese New Year cookies and bake a simple sweet cupcake for my little girl 7th birthday! With plenty of leftover egg whites after baking cookies, this white cake base recipe from Baking Taitai comes in handy! Instead of using vibrant rainbow colours, I chosen pastel shades for this marble rainbow cupcakes. It turned out so sweet and pretty, perfect for my sweet little gal!!! ^0^ closer look....ooh loving the swirl of smooth and silky buttercream sitting on the…