Season chicken with ½ tsp salt and pepper to taste. Coat skillet with cooking spray. Over high heat, sear chicken until browned on both sides, about 2 minute each.
Remove chicken from skillet and set aside. Lower heat to medium.
Add onion and garlic to the skillet and sauté until they are soft, about 3 minutes.
Add rice to skillet with the veggies and toast the rice for a minute or two.
Add stock, remaining salt, and red pepper flakes to the skillet. Bring to a boil, cover, and lower to a simmer or low heat. Cook for 8 minutes.
Remove cover and layer broccoli and chicken over the rice. Cover again and continue to cook for another 7 minutes.
Remove skillet from heat. Stir in ⅓ cup of cheese into the rice mixture. Top with remaining ⅓ cup. Cover skillet again for about 5 minutes, or until cheese melts.
