1. Heat oven to 450 degrees .
2. Gently lift skin from breasts and legs and season chicken with 1 tsp of the Montreal seasoning. Place lemon and garlic slices under skin.
3. Place chicken on a rack in a large roasting pan. Roast at 450 degrees for 30 minutes. Reduce temperature to 350 degrees . Roast for 50 minutes or until internal temperature registers 165 degrees .
4. Meanwhile, place vegetables on a large rimmed baking sheet and toss with olive oil and remaining 1 tsp Montreal seasoning. Place in 350 degrees oven and roast for about 45 minutes or until tender. Stir after 25 minutes.
5. Pour out all but 3 tbsp of the pan drippings from roasting pan and whisk in flour. Cook over medium-high heat for 1 minute; whisk in chicken broth and 1/2 cup water. Simmer 3 minutes, until thickened, scraping browned bits from bottom of pan. Strain.
6. Serve chicken with gravy and vegetables.