How do I get my toddler (18 m) to stop wearing her plate as a hat once she's done eating?

I'm seriously lost here. My 18 month old plays so much with her food that I've taken to putting a towel down under her high chair at meals so I don't have to mop every day. I've tried feeding her myself but she'll refuse to eat. I try to keep an eye on her to remove the plate as soon as she starts playing, but she cries and acts like she's still hungry. Sometimes it happens so fast, like I'm taking a bite of my own food and all of a sudden shes pouring her milk on her head. Is this just an age thing where she's exploring and I wait it out, or do I need to get disciplinary with her? I hate taking her plate away because it feels like restricting food and she's already pretty lean (23rd percentile in weight). Any tips would be great. I'm getting pretty tired of picking rice out of her hair daily.