Place rack in center of oven then preheat to 350 degrees. Coat a 9" x 13" casserole dish with cooking spray then set aside. Add uncooked quinoa, water and ½ tsp salt to a medium saucepan then place over high heat. Bring to boil, reduce heat to low, cover and then let simmer for 20 minutes until liquid is absorbed and quinoa is tender.

Season both sides of chicken breasts with salt and pepper and place chicken in prepared casserole dish. Bake for 18–20 minutes while the quinoa is simmering. Remove from oven and set aside to cool slightly.

Place a large skillet with high sides over medium heat and melt butter. Add onions and ¼ tsp salt then cook for 3–4 minutes, until the onions become translucent.

Add flour, stir until dissolved then cook for 1 minute. Slowly whisk in milk and stir until no lumps of flour remain. Stir in garlic powder and paprika then bring to a boil. Reduce heat to low and simmer for 5 minutes, stirring constantly.

Add shredded cheese and Parmesan cheese in increments, stirring after each addition until completely melted before adding the next. When the cheese is incorporated and the sauce is smooth, remove from heat then stir in the quinoa and chopped broccoli.

Transfer chicken breasts to a cutting board and dice or shred into bite-sized pieces then fold chicken into broccoli-quinoa mixture. (Chicken may be ever-so-slightly undercooked at this point, but don’t worry, it will finish cooking in the oven.) Remove any liquid from casserole dish and re-coat with cooking spray.

Transfer mixture back into casserole dish and bake 35–45 minutes until hot and bubbly. Remove from oven and let cool 10 minutes before serving.