Alot of good ideas posted.
You might find some interesting info here http://www.cancer.org/treatment/survivorshipduringandaftertreatment/nutritionforpeoplewithcancer/nutritionforthepersonwithcancer/nutrition-during-treatment-recipes
Sometimes the medications and treatments effect the senses. (taste & smell) Taste and smell changes there are also recipes to try Recipes to try
Adding "a touch" of different spices can conjur up good memories for her, such as cinnamon and vanilla.
Tomato soups with basil
Make a potage (potato soup) potassium is good, with alot of vegetables and stock. I don't know if you own a stick blender/magic wand ? But all you need to do in stick it in the pot and blitz it. If it is too thick , add stock or water to thin it.
Beet soup is good, carrot soup with a pinch of nutmeg . Squash season is starting , they make for a nice soup as well. A good beef broth to sip on (made with beef and vegetables)
You said :
"I made a simple chicken soup recipe with Mexican Fideo pasta. Although she can't eat the carrots, I cut them large enough to cook and later separate from the soup."
Instead of removing the carrot , you could always mash/puree it and put it back in the soup.
You can also make protein drinks for her.
Dan, I am so sorry that you are going through this.
At Cheftalk, its not just about the food, we care too.
ps. being a caregive is not easy Being a Caregiver