Preheat oven to 400°F (200°C). Butter an 8-inch (2 L) square dish.
In a large pot, bring broth to a boil. Add potato, carrots, parsnips and squash; simmer covered for about 10 min or until vegetables are tender. Stir in peas. Cook covered 2 min. Reserving broth, drain vegetables. Transfer vegetables to a large bowl along with chicken. Check to make sure you have 2 cups (500 mL) of broth left; if not add a bit more broth or milk.
Melt butter in a large skillet set over medium heat. Add onion and garlic. Cook, stirring occasionally, for 3 min. Stir in thyme, mustard, basil, salt and pepper. Sprinkle with flour; cook, whisking, for 1 min. Gradually whisk in milk and reserved broth. Bring to a boil and reduce heat. Whisk for 3 to 5 min or until smooth and thickened.
Pour sauce over vegetable mixture; stir until well coated. Transfer to prepared dish.
Topping: Place 1 sheet of phyllo on work surface; brush entire phyllo surface with butter (keep remaining phyllo covered with plastic wrap and a damp towel). Lay second sheet on top of first; brush with butter. Repeat with remaining 2 sheets of phyllo.
Cut phyllo into 4 equal-sized rectangles. Crumple a rectangle slightly; place on 1/4 of filling, tucking edges on inside of dish. Repeat with remaining phyllo rectangles, on other 3 quarters, covering entire surface of filling. Bake for 20 min or until filling is hot and bubbling and phyllo is golden. Let stand for 10 min before serving
|SERVING SIZE: 6|