Well... her parents may NOT have exposed her to a wide variety of foods before she turned 2ish (the brain classifies new chemicals as posionous and combines that classification with a gag-yuck-spit-it-out! response. Similar, if you took a bite of dog poo... it's a whole body physical reaction... and it can't be helped. In fact, the more foods that get introduced that aren't on the brain's okay list get added to the VILE! list.). This response wears off at around age 5. (but warning... anything that has been classified as VILE! Poison! can remain on that list for a good 10-20 years. It gradually wears off... but it really does take decades and some massive hormonal switching for it not to taste like poo. Quite literally, the tongue CANNOT taste new things between apx ages 2-5. It just makes the body spit it out. No flavor except "yuck".
ANYHOW... assuming this is the probable cause (it's USUALLY the cause for picky eaters, the 2nd most common is a sensory processing disorder related to texture or supertasting... but that is a DISTANT 2nd)... the way to "work around" it is to NOT offer new foods.
Instead, offer the same foods made differently.
Mac'n'Cheese translates to the specific cheeses that are in the mac and wheat. Grilled cheese will *sometimes* work... but NOT if the bread has been caramelized (different chemical signature) unless she's had grilled bread in the past (and it sounds like NOT since she won't eat toast, either), and NOT if it's a different kind of cheese (cheeses have different proteins and microbes in them, which the brain can spot a mile away).
So you find a cheese she's been known to eat (say, american or cheddar or mozzarella) and you use THAT cheese (or cheeses). Cooked wheat flour = bread, tortillas, rolls, croissants, noodles, etc. If she'll also eat eggs... you've got:
- quesodillas (and chicken quesadillas)
- croissant-wiches
- quiche
- pasta carbonara
- etc.
If she'll eat peanut butter (and I'm willing to lay money she'll eat chicken, since most "toddler food" -aka the primary cause for picky eaters is the 11 ingredient NO SPICE NO SEASONING list of what's in gerber and other brand's toddler meals- includes unseasoned chicken)... you've got chicken satay (just thin the peanut butter out with something she likes like yogurt, but don't add any other spices or herbs or sauces to it... ANY chem sig her brain hasn't processed will make the entire dish be rejected, and may add the other foods onto the "yuck" list... creating an even pickier eater).
If you FEEL like it... send me a 'complete list' of what she'll eat, and I can give most people 40-50 different meals using only those items on it (I've done it for picky eaters before, whether it's chem sig issues, or texture issues... but texture issues are harder, because you have to work with the kids to find out what they like about certain textures and dislike about other).
BUT REALLY... is the short list boring YOU or HER? Usually it's the adults who are bored, and the kids are happy as clams. If she's happy with eggs on monday, mac n cheese on tues, and pbj on wed... you might save yourself the grief of cooking 'work around' meals... and just wait a year for it to wear off. UPSIDE: Kids need high fat diets for brain development and the mylenization of nerves (which, at last reading has gotten pushed to 5yo... 10 years ago it was pushed to 2yo, then 4, and now they're finding nerves are still coating at age 5). So while those things would be terrible in an adult diet (the high fat), they're actually pretty healthy for her neural development.