How to Make It
Preheat oven to 350°.
Bring 2 cups water, peppercorns, garlic, and bay leaf to a boil in a large saucepan. Add chicken to pan; reduce heat and simmer, partially covered, 15 minutes or until chicken is done, turning after 10 minutes. Place chicken on a plate; cool slightly. Remove garlic clove from pan; reserve. Shred chicken with 2 forks. Place chicken, salt, 3 ounces Monterey Jack cheese (about 3/4 cup), and green onions in a bowl; stir to combine.
Place reserved garlic clove, cilantro, tomatillos, and chiles in the bowl of a food processor; process until finely chopped. Add half-and-half and cream cheese; process until smooth.
Coat 2 (8-inch) square glass or ceramic baking dishes with cooking spray. Spread 1/2 cup tomatillo sauce in the bottom of each dish. Arrange 5 tortilla halves over sauce in each dish; top each dish with one-fourth of chicken mixture. Repeat layers once, ending with tortillas and remaining tomatillo sauce. Sprinkle evenly with remaining 2 ounces Monterey Jack (about 1/2 cup). Bake at 350° for 15 minutes. Continue baking at 350° for 10 minutes, or remove 1 dish from oven and follow freezing directions. Divide each dish into 4 pieces. Place 1 piece on each of 8 plates; sprinkle evenly with tomato and cilantro leaves, if desired. Serve immediately.
FREEZE: Cool partially baked enchiladas to room temperature in baking dish. Cover baking dish tightly with heavy-duty foil, or seal with an airtight lid. Freeze up to 2 months.
REHEAT: No thawing needed: Bake, uncovered, at 400° for 45 minutes or until enchiladas are thoroughly heated and sauce is bubbly. Top each serving with tomato and cilantro leaves.