Preheat oven to 350°F. Arrange half of the bacon strips side by side on parchment paper-lined baking sheet. Weave remaining strips over and under to create lattice pattern. Freeze for about 15 minutes or until firm.
Meanwhile, remove neck and giblets from turkey; reserve for roasting pan. Pat turkey dry with paper towel. Whisk together maple syrup, mustard, thyme, salt and pepper; rub all over turkey, including under skin and inside cavity. Tie legs together with kitchen string and tuck in wing tips. Place turkey, breast side up, on rack in roasting pan. Place bacon lattice over top to cover breasts and legs. Arrange onions, celery and carrots around turkey.
Cover with foil and roast for 2.5 hours, basting occasionally with drippings. Remove foil; cook for 30-45 minutes or until thermometer inserted into thickest part of breast reads 165°F.
Remove kitchen string. Transfer turkey to cutting board and tent loosely with foil. Let rest for 30 minutes before carving.
Meanwhile, skim off fat in roasting pan; stir in broth. Cook over medium heat, stirring to scrape up brown bits from bottom of pan; bring to boil. Whisk cornstarch with water; slowly whisk into pan. Simmer for 6-8 minutes or until thickened. Strain and stir in parsley. Serve with turkey and cranberry sauce, if desired.