Wash and dry the cauliflower, then turn it into rice by one of several ways. First cut the cauliflower right down the middle so it breaks up into florets, then mince the florets by either grating in the medium sized hole part of a box grater, using a grater attachment in the food processor, or using a manual vegetable chopper and blitzing a handful of florets at a time.
Once your cauliflower is minced, remove excess moisture by patting it thoroughly with paper towels, and set aside.
Heat the olive oil in a large saucepan over medium heat, then sauté the onion and minced garlic until just softened.
Add the kale, and sauté until wilted, then add in the diced tomato and stir for a couple minutes until tomato releases a little juice. Add in the riced cauliflower and stir for a minute or so until mixed well.
Add the chicken broth and cooked shredded chicken, and cover and cook for 5-8 minutes, then remove lid and let it cook for another 5 minutes or so until liquid has completely evaporated.