Or how about some ice cream, and they can put it on the waffles if they wish? Plus toppings - chocolate and caramel syrup, chocolate chips and peanut butter chips, whipped cream, sprinkles, M&Ms, cherries, fruit, etc.
I'll agree with some of the others and say that for a kid's birthday party, cake or cupcakes makes sense no matter the time. Heck, I would say that for an adult bday party too. Besides, true brunch includes lunch items and cake absolutely makes sense as a dessert for lunch.