Help! Picky eating

Ana

So my daughter is low on iron and I've been trying everything. She will pick out the spinach and go around all the meat on things. I've tried mixing in little bits of spinach into mac and cheese and I get a full on tantrum. She used to be a perfect eater, loved veggies but it's been a whole month now that she refuses to try meat or veggies. She likes some of them and will eat chicken but most high iron foods she hates. Anyone have any tips, I really want her to be happy and healthy. We eat the same things she does and she still doesnt trust it.