This recipe makes enough enchiladas to feed a crowd, but the leftovers reheat great! You can use store bough salsa verde if you really want to, but the fresh tomatillo salsa really adds a ton of flavor to the dish and is simple to make.
Heat oven to 400*F. Place chicken in a large stock pot and cover with water. Add salt and cover. Simmer 20-25 minutes, until cooked through. Allow chicken to cool slightly, then shred.
Meanwhile, add the tomatillos, garlic, onion, jalapeno, 1/2 cup cilantro, vinegar, sugar, and lime juice to a food processor or blender. Process until smooth, about 30 seconds.
Ladle 1/2 cup of salsa into the bottoms of two small baking pans. Place a single layer of tortillas (about 2) over the salsa. Top with 1/3 of the shredded chicken and Monterrey Jack Cheese. Top with 2 tablespoons salsa and cover with an another layer of tortillas. Repeat, creating a total of 4 tortilla layers in each pan. Top with remaining salsa and Monterrey Jack.
Cover with foil and bake 20 minutes. Remove foil and bake another 10 minutes.