Possible Clues:

• Foodstuff consumed in most of France at one time
• Calorie-laden cake
• Pays to get in to get first prize for cake
• 21 (not half) takes tea and cake
• Dessert, or tea in most of France at one time?
• Before last of tiramisu nibbled into edges of Genoa cake
• Cake (French)
• People in attendance getting a first piece of unusual cake
• Eating a tea usually includes this
• Cake and Vichy water on grant, oddly