babysitter starved my child

I have an 11 month old. the babysitter only gave her 12 oz all day today. when i got home and was told this I made a bottle right away and woke her and she just chugged that bottle so quick. what do I need to do legally if anything?

I feel I should give yall more info. the sitter is actually the parents. I am the legal guardian though. but they plan on trying to get her back so I decided to see how it went for the day with them in charge because I'm cool with them getting her back IF they can take care of her. they were starving her before she was placed in my care so she is skin and bones but she has gained some weight being with me. I told them how much she eats and the dr has said she needs 4 bottles a day. I figured they would listen and this was their shot and they hardly fed her. sorry guys its complicated and all I want is for this baby to be in good hands.