In a large mixing bowl, combine riced cauliflower and shredded hashbrown potatoes.
Add cream of chicken soup and yogurt and mix till cauliflower and potatoes are coated.
Mix in salt, pepper and garlic powder.
Add in shredded cheese and mix well.
Pour mixture in a 9x13 inch baking dish and top evenly with butter slices.
Bake casserole at 350 degrees for 1 hour. Then turn to broil and continue for 5 more minutes till casserole is golden brown and bubbly.
Remove casserole from oven and let sit for 10 minutes to thicken.