Possible Clues:

• Dressed in yellow and white?
• Like good French toast
• Like frittatas
• Say 'heartlessly merry' describes a foolish-looking person's face?
• Like an omelet, e.g.
• Like brioche
• Like part of breakfast Margaret hasn't started?
• Like things hens lay
• Margaret's shed painters initially daubed in yellow and white?
• Like an omelette? For starters, extremely good Greek yoghurt