Preheat and prep: Heat your oven to 375°F (190°C).
Lightly grease a 9x13-inch baking dish.
Cook the veggies: Warm the oil in a large skillet over medium heat. Add celery, carrots, and onion with a pinch of salt. Cook 5–7 minutes until softened.
Stir in cauliflower rice and cook 3–4 minutes more to release moisture. Remove from heat.
Make the sauce: In a large bowl, whisk the Greek yogurt, Buffalo sauce, eggs, garlic powder, onion powder, smoked paprika, and a good crack of black pepper. Taste and adjust salt if needed.
Combine: Add the shredded chicken and the cooked veggie mixture to the bowl.
Stir until everything is well coated. Fold in half of the shredded cheese.
Assemble: Spread the mixture evenly in the baking dish. Sprinkle the remaining shredded cheese on top.
Bake: Place on the center rack and bake 25–30 minutes, until set in the center and bubbling at the edges.
Finish: If using, sprinkle blue cheese over the hot casserole and let it rest 5–10 minutes.
Garnish with chopped parsley or chives.
Serve: Scoop into bowls. Add extra hot sauce, a squeeze of lemon, or a drizzle of light ranch if you like.