EULA

Don't be surprised if these 'battles' don't end. See what happens when you stop controlling minute aspects of her life. If she goes to bed late or eats too many cookies, it's not going to do her any harm, certainly if it's only for a few days. She wants independence, so give it to her.

I don't have children so take this as you will, but I think you'll find parenting a lot less frustrating if you let her do whatever she wants. Permissiveness is often conflated with negligence, which I don't think is wise. People will say that you're spoiling her, but spoiled children are children who are given things instead of love.

If you do this for a week, the first few days she'll make herself sick eating cookies and will go to bed late just because she can, but by the 4th day she'll become more "sensible".