Let me reassure you both that it does get easier and tidier too.
They are just in one of the many fazes that kids go through. I can remember on eof my friends kids loved my casserole one visit. A couple of weeks later there was no way he was going to eat any food that was touching something else. Made Spaghetti Bolognaise hard to serve up I tell you!
My advice would be not to stress over it (I know, easier said than done) but try to make sure that you give them the healthy options.
It's hard to please them while not giving in to them too. But you will find your own balance here I'm sure.
Keep up the good parenting and don't forget the messy mat if you need it!