Prep the chicken: Poach, grill, or bake chicken breasts until cooked through, then shred with two forks. You can also use rotisserie-style chicken breast to save time.
Heat the oven: Preheat to 375°F (190°C).
Lightly spray a 9x13-inch baking dish with olive oil.
Cook the veggies: Microwave cauliflower rice until just tender and excess moisture steams off. If using broccoli, steam until crisp-tender, then pat dry. Dry veggies mean a creamier casserole.
Make the creamy base: In a large bowl, whisk Greek yogurt and softened cream cheese until smooth. Stir in ranch seasoning, garlic powder, onion powder, smoked paprika (if using), pepper, and salt.
Stir in the good stuff: Fold in shredded chicken, cauliflower rice or broccoli, half the cheddar, all the mozzarella, most of the green onions, and half the turkey bacon.
Assemble: Spread the mixture evenly in the prepared baking dish.
Top with remaining cheddar and the rest of the turkey bacon.
Bake: Bake uncovered for 18–22 minutes, until the casserole is hot and the cheese on top is melted and lightly golden.
Rest and garnish: Let it stand 5 minutes to set. Sprinkle with remaining green onions. Slice and serve.