I'm not an expert, but would imagine that living on rice, bread, pasta & spuds (with some milk) might leave her open to a risk of vitamin deficiency. Plus there is not much protein there to help with growing muscles etc. And of course, there is a concern that your daughter's palate will be too limited (although toddlers are notoriously neophobic about food, so she may grow out of this stage).
Does she like cheese? I often kid my DS into eating things he is less keen on by covering them with cheese sauce. As Suiledonn says, you could make a chicken stock (from a chicken carcass, rather than a cube) and use that as the basis of a bland soup, e.g. butternut squash, adding in a bit of cream to make it more palatable for her. As a real stock it will contain some protein.
From what I've read, it's important not to make meals into a stand-off, but I can't see how you would not feel frustrated and concerned if you offer your child a healthy diet and end up binning most of it. At 2, my DS has just started responding fairly well to an "eat 3 more spoons of your lunch if you want your pudding" type negotiation. If your little one's language/reasoning is up to that, perhaps you try it, or offer protein/veg only for a couple of days).
Like I say, am no expert, perhaps someone else will be able to offer advice, so BUMP!!