1. Preheat oven to 350F. Spray a 9x9 square baking dish with nonstick cooking spray and set aside. 2. Heat oil in a large skillet over medium heat. Add onions and celery and sauté for 2-3 minutes. Sprinkle with flour and cook for an additional 1 minute to allow the flour to cook. Stir in chicken stock, cumin, salt, and cayenne pepper. Add chicken and spinach and mix to combine (if mixture appears too dry, add more chicken stock). 3. Fill each tortilla with the chicken mixture, roll up, and transfer to prepared baking dish. Top with 1/2 cup salsa and cheese and bake for 10-12 minutes until cheese is melted. Serve with additional salsa and diced avocado. Mario's Tips: - Pick chicken from 2 rotisserie chickens for this recipe. - Reserve the bones and scraps from the rotisserie chicken to make your own chicken stock.