Preheat oven to 325, in a medium bowl cream together sour & cream cheese. Stir in 1/2 cup of the salsa & 1 cup of shredded cheese.
In a second bowl, toss together the chicken, corn cumin, salt, pepper & 1/2 of the scallions, add the chicken mixture to the cream mixture and stir to combine.
In the baking dish, spread 1/2 cup of the salsa over the bottom. Place about 1/3 cup of the filling on a tortilla, roll up & transfer to the baking dish seam side down. repeat process for remaining tortillas.
Pour remaining salsa over enchiladas, spreading to cut all of them. Sprinkle remaining cheese over the top. Enchiladas may be made up to this point 12 hours in advance.
Transfer to preheated oven & bake 20-25 min 'till hot & bubbly. Sprinkle w/ remaining scallions & serve serve warm, it may be reheated cover w/ aluminum foil...