First rule of parenting: Give in right away or not at all. If it’s been long enough to type this post, you’re going to have to ignore the screaming for dessert until they fall asleep from exhaustion because if you give in now, all you’ve done is encourage tantrums.

Distract the kid, take em for a walk, talk to them in whispers until they quiet down enough to hear your and then tell them knock knock jokes.

Literally anything that’s not giving them dessert.