Preheat the oven to 350°F (175°C).
If desired, place the chicken in a bowl and season generously with salt. Let it sit while preparing the remaining ingredients for extra tenderness.
Add cottage cheese, buffalo sauce, garlic, dill, parsley, onion powder, celery salt, salt, black pepper, and cayenne pepper to a food processor. Blend until completely smooth.
Heat olive oil in a large skillet over medium-high heat.
Add chicken, celery, and carrots. Season lightly with salt and pepper. Cook undisturbed for about 3 minutes.
Stir and continue cooking for another 3 minutes until the chicken is lightly browned. It does not need to be fully cooked.
Thaw the cauliflower rice in the microwave or on the stovetop until warm.
Place the cauliflower rice in a clean kitchen towel or paper towels and squeeze out as much moisture as possible.
Add the cauliflower rice, cooked chicken mixture, green onions, and blended buffalo sauce mixture to a 9x13-inch baking dish.
Stir everything together until evenly combined.
Cover with foil and bake for 20 minutes.
Remove the foil, sprinkle shredded cheddar cheese over the top, and bake uncovered for another 10 minutes.
Switch the oven to broil for 2–4 minutes until the cheese becomes golden and bubbly.
Top the Creamy Buffalo Chicken Casserole with additional buffalo sauce, ranch dressing, and fresh green onions before serving.