Step 1NOTE: If you have never worked with phyllo before, don’t be afraid! Read the box directions carefully and have everything prepared to assemble before you open the phyllo. (And, it is pronounced “fee-low.”).Step 2Pre-heat oven to 350 degrees F. Coat a round casserole dish with non-stick cooking spray.Step 3In a large non-stick skillet, add ½ tsp olive oil and heat over medium heat. Add the chicken pieces, seasoning with salt and pepper. Cook through until no longer pink. Remove to a plate.Step 4Add remaining oil, onion, garlic, and celery to skillet; cook 3 minutes. Stir in flour and cook 1 minute, stirring constantly. Gradually stir in broth and half-and-half. Cook, stirring until mixture comes to a slight boil.Step 5Add frozen vegetables, salt and pepper to taste. Cover and cook on medium/low, simmering and stirring occasionally, about 10 minutes.Step 6Stir in chicken, parsley, and sage. Remove from heat and keep warm.Step 7Unroll phyllo. Remove 2 sheets to the counter and spray them lightly with cooking spray. Place them in the bottom of the casserole dish so they cross each other, and run up the sides.Step 8Spoon the chicken mixture into the casserole dish. Sprinkle with parmesan cheese. Fold phyllo over the top. Remove 2 more sheets, coat with spray, and place them on top of the pie so they cross each other. Tuck the edges down the sides as best you can.Step 9Cook at 350 degrees for 35-40 minutes, until hot and bubbly inside. Let stand 5-8 minutes before serving.