To prepare stock, combine first 10 ingredients in a medium saucepan; bring to a boil. Reduce heat, and simmer 25 minutes. Strain through a cheesecloth-lined colander into a bowl, and discard solids. Set aside 3 cups stock; reserve any remaining stock for another use.
To prepare rice, place poblano chiles on a foil-lined baking sheet; broil 8 minutes or until blackened and charred, turning after 4 minutes. Place in a zip-top plastic bag; seal. Let stand 15 minutes. Peel and discard the skins. Cut a lengthwise slit in each chile; discard seeds and stems. Set chiles aside.
Heat oil in saucepan over medium-high heat. Add 2 cups leek and rice; sauté 5 minutes. Add 2 3/4 cups stock, 3/4 teaspoon salt, and bay leaf; bring to a boil. Cover, reduce heat, and simmer 18 minutes or until liquid is absorbed. Remove from heat; discard bay leaf. Fluff rice with a fork.
Combine 1/4 cup stock, roasted poblano chiles, parsley leaves, and cilantro leaves in a blender or food processor; process until smooth. Gently fold chile mixture into the rice. Sprinkle with Monterey Jack cheese.