Hi, C.. Well, the thing with discipline is that it takes repetition, and it doesn't always have immediate results. It sounds like you have the situation under control, even though it doesn't necessarily feel that way.
Your daughter is at the age where small children are just OVERJOYED at seeing that they can do stuff. They are just learning cause and effect, and she feels so very powerful making the food go splat. She is also probably looking for attention -- the attention she lost when she started becoming more independent and feeding herself. You will want to give her the attention she misses in a positive way instead of allowing her to make up for it in a negative way.
Here's what I would do: sit next to her and eat something yourself. Look at her, give her attention while you are both eating, maybe make a contest out of it or a game of I go now, you go now... and **praise her constantly*** for getting the food into her mouth...like every second of the time. If this works, then after a while, praise her every other time, then every third or fourth time, and then get random with your praise. She won't know when you're going to applaud her, so she'll do the right thing more frequently.
I know this is conditioning, and some people think it's more for dogs than humans, but seriously -- if you give children what they need, they will behave better. It sounds like she needs attention, and she's producing negative attention in order to get it. All people do things that give them rewards, and there is nothing wrong with making it very, very pleasant for your child to do what you want her to do.
Also, make sure she is actually hungry when you feed her. I know that kids have to get used to regular mealtimes, but in this case, where you want to get rid of bad table behavior, you might want to be a little more flexible with her mealtimes and only feed her when she is hungry. She will be less likely to waste the food.
Please let us know how you and she do with this situation. I hope eating time goes back to a peaceful, loving time of day for both of you.
Peace,
Syl