adapted from Fine Cooking and Rick Bayless
1 lb tomatillos (about 12 medium), husked and rinsed
3 jalapenos, stemmed and halved lengthwise (seeded, if you like)
1 medium white onion, cut into large chunks
3 garlic cloves
2/3 cup chopped cilantro, divided
2 cups chicken broth
1/2 Mexican creme, creme fraiche or heavy whipping cream
About 2 cups of coarsely shredded cooked chicken, grilled, roasted, or rotisserie
2/3 cup shredded Mexican melting cheese (quesadilla, asadero, or any similar), Monterey Jack, or mild cheddar
12 corn tortillas
Make the sauce
Roast the tomatillos, sliced onion, peeled garlic and chiles on a rimmed baking sheet 4 inches below a hot broiler until the tomatillos are soft and blotchy black on one side, 4-5 minutes. Turn everything over and roast the other side. Remove and reduce the oven temperature to 350° F.
Scrape the tomatillo mixture into a blender, along with 1/2 cup cilantro. Process to a smooth puree. Heat 1 1/2 Tbsp oil in a medium-large pot over medium high heat. When the oil is hot enough to make a drop of the puree sizzle, add the puree all at once. Stir constantly for several minutes until darker and thicker. Add the broth and the crema, reduce the heat to medium-low, partially cover and simmer for about 30 minutes. (You want a soupy consistency.) Taste and season with salt.
Put the chicken in a bowl and stir in 1/2-3/4 cup of the sauce mixture into it.
Finishing the enchiladas
Smear about 1 cup sauce over the bottom of the large casserole dish. Lay the tortillas on a baking sheet (or 2) and lightly brush or spray both sides of the tortillas with oil Bake just to warm them through and soften, about 3 minutes. Stack the tortillas and cover with a towel to keep warm.
Working quickly so the tortillas remain warm and pliable, roll a portion of the chicken and a bit of shredded cheese up in each tortilla, then line them up in the baking dish. Pour the remaining sauce, evenly, over the enchiladas and sprinkle with shredded cheese. Bake until the enchiladas are heated through, about 15 minutes. Garnish with onion rings and remaining cilantro.