I think most of us have confronted some variation of this scenario.
Choosing to not eat breakfast, then being hungry an hour later is called a "natural consequence". Kids learn from consequences. A 10 year-old can survive being hungry for 1-2 hours. It sounded like a rough day, so I'll share how this might have played out differently at my home--
1) You responded to her feeling hungry with frustration. Remember validation and active listening? I deploy it not only on ex's, but also friends, family, and on a good day myself. Aren't they even more deserving? As you practice this skill, it will come more easily, and it will sound more natural.
2) It sounds like you didn't have food she could get herself when she was hungry. I have fresh fruit on hand most of the time but it doesn't always happen. When it doesn't, my pantry has fruit cups in natural juices. When that doesn't happen (fail, lol), I'd put her leftovers in the fridge (even if they rarely eat them).
You: "Oh, your waffles are still here if you want them." D: "I don't like cold waffles." You:"Yeah, they do taste better when they're warm." D: "I don't want them." You: "I respect you're not hungry enough to eat cold waffles." (If you have time) "You know, if you'd like, I'd be happy to teach you how to heat up those waffles." D: <frustrated> "I just want apples." You: "I get you want apples more than waffles. Waffles are what we have now. I'm going shopping today. You can help me pick out fruits so we have some on-hand that you like?"
