1Heat oven to 350. Spray a lg casserole dish w/ cooking spray. Heat oil in lg pot or deep skillet over med-high heat. Add cauliflower, carrots, celery and onions, cook 10 mins.
2In plastic ziplock bag, add flour, chili powder, pepper and paprika. Add chicken to bag and shake to coat. Add chicken to skillet, cook 4 mins, stirring.
3Add milk, bring to a boil until thickened. Add peas, mayonnaise and mustard. Simmer 10 mins, stirring often. Spoon into casserole dish. Spray each phylo sheet w/ a little cooking spray. Layer the sheets over filling in casserole dish. Bake 10 mins, or until heated through and phylo dough is light brown.