Add onion, garlic, brown rice, salt, pepper, and chicken broth into the slow cooker. Stir to mix well.
Place chicken breasts on top of the rice mixture and drizzle with olive oil.
Cover and cook on HIGH for 3–3.5 hours. Rice should be tender, chicken fully cooked (165°F), and most of the liquid absorbed.
Remove chicken from the slow cooker and let rest for 5 minutes. Cut into 1–1½-inch pieces.
While the chicken rests, blend the cottage cheese, tamari, poultry seasoning, onion powder, and garlic powder until smooth.
Return chopped chicken to the slow cooker. Add broccoli florets and the blended cottage cheese mixture. Stir gently. Sprinkle cheddar cheese on top. Cover and cook 15–20 minutes until broccoli is tender, cheese is melted, and everything is heated through.
Turn off the slow cooker and enjoy warm.