Combine first 5 ingredients in medium saucepan. Using mallet or back of large spoon, lightly crush or bruise spices. Add 6 cups water; bring to boil over high heat. Reduce heat to medium-low, partially cover pan, and simmer gently 10 minutes. Remove from heat. Add tea bags and steep 5 minutes. Discard tea bags. Add milk and sugar. Bring tea just to simmer over high heat, whisking until sugar dissolves. Strain chai into teapot and serve hot.