How to Make It
Place the chicken in a large pot, add enough water to cover, and bring to a boil. Reduce heat and simmer until cooked through, 25 to 35 minutes; remove from pot and let cool. When cool enough to handle, shred the chicken, discarding the skin and bones. Divide the chicken meat between 2 large bowls.
Meanwhile, in a blender, working in batches, puree the salsa, cilantro, and 2 cups of the sour cream until smooth; transfer to a medium saucepan as you work. Simmer the sauce until slightly thickened, 15 to 20 minutes; stir in the remaining 2 cups of sour cream.
To each bowl of chicken, add 1 package of corn, 1 cup of the sauce, 2 cups of the cheese, and 1 teaspoon each salt and pepper and toss to combine.
Spread 1 cup of the remaining sauce in each of four 9-by-13-inch baking dishes (4 cups total). Roll the chicken mixture in the tortillas (about ½ cup per tortilla) and place seam-side down in the dishes (8 rolls per dish). Top each dish of enchiladas with 1 cup each of the remaining sauce and cheese.
To eat tonight: Bake the enchiladas at 400° F until bubbling and beginning to brown, 15 to 20 minutes.
To freeze and cook later: Freeze the unbaked enchiladas, tightly sealed, for up to 3 months. To cook, thaw the enchiladas and bake, uncovered, at 400° F until heated through, bubbling, and beginning to brown, 25 to 30 minutes.