Heat the oven to 350 degrees. Poach the chicken by placing the thighs in a saucepan and covering it with water. Add one onion, peeled and quartered; the bay leaves; 2 smashed garlic cloves; oregano and 1/2 t salt. Bring to a boil and reduce heat to medium low. Cook for 15 to 20 minutes until the chicken is cooked through. Remove chicken from the pot and allow to cool. When the chicken is cool enough to handle, shred it and set aside.
Heat the broiler to high. While the chicken is cooling roast your tomatillos and the peppers in two separate broiler pans. The goal is to char the skin on both the tomatillos and the peppers. Check every 3 minutes or so and turn when one side has blackened. The tomatillos will release their juices. Save this juice for the sauce. See my tomatillo post for pictures on charring.
When the tomatillos are charred and the skin is partially blackened, remove the pan from the broiler and set aside to cool. When the peppers are charred remove from the pan and put in a closed paper bag to steam for 5 minutes. Slip the poblano pepper skins off with your fingers, remove the seeds and chop. Do the same for the jalapeno peppers, reserving one jalapeno for the sauce and one for the chicken filling.
Once the tomatillos have cooled remove any hard core that remains, and put all the tomatillos, their charred skins and the juices that have collected in the broiler pan into a blender. Add 1/2 bunch of cilantro, including stems; 1 seeded and chopped jalapeno; and 1/2 t salt. Whirl in the blender until well combined. Taste and adjust seasoning.
Slice the remaining onion into 1/4″ rings. Add 1-2 T olive oil to a hot skillet and saute the onions with 1 t cumin, 3 chopped garlic cloves and a pinch of salt for 5 – 6 minutes, until the onions are soft and beginning to caramelize on the edges. Add the chicken, the chopped poblano peppers and one seeded and chopped jalapeno pepper. Stir to combine and set aside.
Put the tomatillo sauce in one skillet and place on the stove and heat on medium low until hot. Reduce heat to very low to keep warm. In another skillet, add about 1/4 cup olive oil and heat to medium high.
Ladle about 1/3 cup of tomatillo sauce into the bottom of a 13 x 9 x 2″ rectangular or a 12″ round baking dish and spread it around to coat the bottom of the dish. Mix the two cheeses together in a bowl and set aside.
Now you begin the assembly of the enchiladas. Take one tortilla and fry it for about 5-8 seconds on each side. Remove the tortilla from the oil and dip it in the tomatillo sauce to coat both sides. Remove the tortilla from the sauce and place it on a plate you will use to assemble the enchiladas. Put about 1/3 cup of the chicken filling down the center of the tortilla. Top with about 1 T of the combined cheeses. Roll up like a cigar and lay seam-side down in the baking dish. Continue until all the enchiladas are assembled and nestled side-by-side in the baking dish.
Pour about 1 cup of the remaining sauce over the enchiladas. Sprinkle the center of the enchiladas with the remaining cheese and bake for 20 to 30 minutes until heated through and cheese has melted.
Garnish with chopped tomatoes, cilantro leaves, green onions and Mexican crema or sour cream. If you have any extra tomatillo sauce you can serve it with the enchiladas.