What to do with fava-garbanzo flour?
Why not try making a test batch of socca? Or pakoras? I have no experience with fava flour, but I've used both dried favas and dried garbanzos and a combination of both to make falafel and they cook up exactly the same and the difference in taste is subtle.
Hummus might work. Cook it up like cheese boy suggests (except you do want it a bit loose) and add olive oil, lemon juice, tahini, etc.
Cook it up like polenta on your stovetop taking caution to not make it very loose. Then, allow it to cool a bit in your serving bowl, and top it off with evoo, tomato sauce, or grated cheese of your choice. Be liberal with your salt if you can also ... you'll need it.