Preheat oven to 350 degrees. Grease 9x13 pan with oil spray (I use a Misto).
In a medium saucepan bring chicken broth to boil on high heat. Add in quinoa, bag of cauliflower rice and ¾ tsp dried oregano and bring back to a boil. Then turn down to low, add lid and allow to simmer for 15 minutes.
Meanwhile, in a large non-stick skillet, heat 1 tbsp oil until it shimmers on medium heat. Season both sides of the chicken tenders with salt, pepper, garlic powder and ¾ tsp oregano. Cook chicken in skillet on both sides until fully cooked, about 10 minutes.
While the chicken and quinoa are cooking, heat 1 tsp oil in a medium-sized pot on medium heat. Add in minced garlic and saute for 1 minute or until slightly golden on edges. Then stir in spinach by the handful and cook for about 3-4 minutes or until wilted. Pour in jar of marinara and simmer for 2-3 minutes on low to warm through.
Once quinoa & cauliflower mixture is cooked, add half of the spinach marinara sauce and stir to combine. Then pour the quinoa mixture into the 9x13 pan and smooth out. Top with the chicken tenders and then pour on the rest of the sauce. Finally, top with the mozzarella and Parmesan cheese.
Bake casserole for 15 minute or until cheese has melted. Serve warm.