Preheat oven to 400 F and grease a 13x9” casserole.
In a small bowl, mix together the milk and the cornstarch or tapioca starch.
In a large bowl, mix together the cauliflower rice, broccoli, bell pepper, chicken, milk and starch mixture, cream cheese, 1 cup cheddar, 1 cup mozzarella, oregano, garlic, onion, paprika, chili if using, pepper and salt.
Toss to mix very well and transfer to the casserole dish.
Top with the remaining ½ cup of cheddar and ½ cup of mozzarella. Bake for 45 minutes uncovered or until golden brown. Allow to sit for 5 minutes before topping with parsley and enjoying.
Want to freeze this for later? Once you've baked the cauliflower rice casserole and allowed it to cool, simply wrap it up tightly with plastic wrap or aluminum foil and transfer to the freezer. When ready to enjoy, allow it to thaw overhead in the fridge overnight before heating it through in the oven.
I would suggest shredding your own cheese as pre-shredded cheese have a flour coating on them that prevents them from clumping. However, this makes it grainy when melted. To quickly shred a block of cheese, you can use a food processor.
If you do not want to use cooking spray in your baking dish, you can use parchment or tin foil but your dish might still stick to it. You can always grease your pan with butter or olive oil as an alternative to cooking spray.