Preheat the oven to 350°F. Spray a deep 13 x 9-inch casserole dish with cooking spray. Set aside.
Cook the rice per the package instructions just until tender then drain and cool. This can be done in advance, if desired. Do not overcook.
In a medium size mixing bowl, whisk together the broccoli cheese soup, cream of celery soup, mayonnaise, evaporated milk, pimientos, butter, rotisserie chicken seasoning, garlic salt and lemon pepper.
Add the cooked rice, chopped chicken, 2 cups cheese, steamed broccoli and green onions. Stir until fully combined.
Pour into the prepared dish, then sprinkle with the remaining 1 cup of shredded cheese.
Bake for 35-45 minutes until heated through and bubbly around the edge.
Rest for 5-10 minutes, then serve.