I'm usually the last to agree with too much control and angst over what parents give their kids to eat or deny from them because it usually backfires and the kids go mental and can't control themselves when they get to choose (My DN, for 2 examples) but your little one is only 14m old!
I didnt let my DS eat too much crap when we lived abroad, the idiot locals are pretty infamous for being unhealthy eaters and arrogant too, so would constantly try to give DS crap. The arguments I'd had with STRANGERS trying to give my DS a packet of crisps!
Your little one doesn't need all that crap all the time, no, a bit here and there with a good reason is fine, but your childminder is in the wrong.
That's an area you can agree to disagree on, my issue with this is that you have been really clear about things, and your 'instructions' for want of a better word have been clear and she is ignoring them. You're right to move her to another childminder
Up to you if you tell her and give her the honest feedback, but tbh, she's not bright enough to have understood what you told her before, so her spin on it will be "Oh @Grabmygran is so unfair, she's sacked me cos i gave her DD a chockkie bickkie."
Just say that you have found a childminder that suits your family better and thanks for all her efforts thus far...