Preheat oven to 425F. Add cauliflower steaks to a baking dish or sheet and spray or brush each side with olive oil. Season both sides with salt & pepper. Transfer to the oven and roast for 10 minutes.
Meanwhile, in a small bowl mix together the salt, paprika, garlic powder and onion powder. Rub this spice mixture onto both sides of the chicken breasts.
Once the cauliflower is done roasting, remove it from the oven and reduce the oven temperature to 400F.
Brush the cauliflower with some of the BBQ sauce, add the seasoned chicken breast on top, then brush with the remaining BBQ sauce.
Top with some of the shredded cheese, then a few slices of red onion and more cheese. Transfer back to the oven to cook for about 20 more minutes or until the chicken reaches an internal temperature of 165F. I like to switch to broil for the last few minutes to give the cheese some color!
Finally, serve with an extra drizzle of BBQ sauce and some more chopped red onion and parsley, if desired. Enjoy!