Not sure if this is too heavy on tomatoes, but I make this Smitten Kitchen ziti chickpeas with sausage and kale for the whole family [keeping the kale to one side]. I use a mix of cannelini beans and chickpeas and sub our favorite jarred marinara sauce. If you use lean chicken Italian sausage, he could get away with not even pre-browning it and just squeezing chunks into the sauce once it’s heated up in the slow cooker.
ETA: this salsa verde chicken with black beans and hominy could also work well in a slow cooker.
