Preheat oven to 350°F. Spray a 13x9 inch casserole dish with cooking spray.
Heat olive oil in a large pot or deep skillet over medium-high heat. Add the ground chorizo and onion and cook until chorizo is browned and onion is softened, about 5-7 minutes. Do not drain grease.
Add cooked cauli-rice and garlic to the meat and onion in the pan and mix well. Saute until garlic is fragrant, about 30 seconds. Transfer the mixture to the casserole dish and set aside.
In a large bowl, combine the cream of chicken, milk, sour cream and seasonings. Whisk well. After the sauce is mixed, stir in the Rotel and the beans. Pour the finished sauce over the cauliflower and chorizo mixture and stir through, ensuring all of the cauliflower is coated and the beans and tomatoes are well distributed throughout.
Evenly spread the cauliflower mixture over the casserole dish and top with cheese. Bake uncovered for 20 minutes or until the cheese is bubbly and the sauce and beans are heated through.
Let cool for 10 minutes before serving and top with any toppings of your choosing. Enjoy!