- Preheat oven to 425⁰F.
- In a large skillet over medium-high heat, heat olive oil and sauté onion, garlic, thyme and rosemary until onion is tender and fragrant, about 5 minutes.
- Add cooked chicken, mixed vegetables, salt and pepper; cook until heated through, about 5-7 minutes.
- Add cornstarch and broth mixture; bring to a boil, stirring constantly.
- Reduce heat to low and simmer until sauce has thickened, stirring occasionally.
- Transfer mixture to a 9×13 inch baking dish.
- Spray cooking spray evenly to both sides of each fillo sheet and arrange them over top the chicken mixture.
- Bake 20 minutes or until fillo is crisp and golden brown.