Millet Stuffed Chicken Breasts

Preheat oven to 375 degrees F. Coat a 9-inch x 13-inch baking dish with cooking spray. Set aside. Add the olive oil to a nonstick sauté pan over medium heat. Add the onions and asparagus and sauté for 4-5 minutes, or until the onions turn clear. Mix the sautéed vegetables with the cooked millet and set aside to cool. Slice a pocket into one side of each chicken breast that runs the entire length of the chicken breast, without coming out the other side. Once the millet and vegetables are cooled, stuff ½ cup of filling in the pocket of each chicken breast and lay them side by side in the baking dish. Brush each breast with Dijon mustard.  In a small bowl, mix together the breadcrumbs, tarragon, salt (optional), and pepper. Divide the breadcrumb topping among each breast, coating the top completely. Spray each breast with cooking spray and bake for 35 minutes or until the internal temperature of chicken is 165 degrees F. Let the chicken rest for at least 5 minutes before slicing.