Why this style works:
Chenoweth allows the hair to grow below the chin which helps elongate her face. When you have a round face and straight hair, you want to avoid chin-length bobs.
Chenoweth sports sleek, graduated layers from her lips down. This helps remove bulk and weight from the sides.
Wispy, tapered ends de-emphasize roundness.
Wear glasses? Find out which frames flatter your face shape in Best Glasses for Your Face Shape.