4 (nearly 5) year old not eating very much

[lololy]

Help!!!
My daughter has never been a massive eater! She's quite petite naturally and I never want to force feed her and cause any long term psychological damage BUT she wastes so much food and it pains me to see it get thrown away or go cold.

I do try to keep leftovers and reheat where I can . But then it only gets left again for a second time and I refuse to keep remaking food in the kitchen !! Can I add here that I do make things I know she enjoys and I try to add something new each time , so it's not like I'm making her awful stuff !

What do other parents do with children who eat little or are particularly fussy?

P.s she will also just sit there and stare at it for ages not eating it until it goes cold . Consequently it is then not nice because it is stone cold!!!
If it was a bowl of chocolate it would be eaten up so fast !

A couple of things that helped us were:

Putting something you know she loves non a plate or in a bowl next to the meal. That way she's eaten something.

Giving her really small portions. She can always have more if she's enjoyed it.

Never, ever, ever offer an alternative.