1. Prepare the green chile: Line the cooking pot of the Multicooker with the poblano peppers. Cover and set to Brown/Sauté at 400°F. Cook for about 30 minutes, removing cover to turn every 8 to 10 minutes, until all sides are charred (time will vary depending on the size and quantity of the peppers). Remove, put into a mixing bowl and cover with plastic wrap. Once cool to the touch, peel, seed and roughly chop. Reserve. Carefully clean any of the char from the bottom of the pot before using for the next step.
2. Put oil into the cooking pot and again set to Brown/Sauté at 400°F. When the oil is hot, add the onion, jalapeño and garlic to the pot. Stir and sauté until softened and slightly golden. Stir in the flour and cook for about 1 to 2 minutes. Whisk in the broth, using a nonstick whisk and bring to simmer until smooth and thickened (about 5 to 7 minutes). Stir in the chicken and the reserved, chopped poblanos, and switch to Slow Cook on High for 3 hours.
3. While the chile is cooking, pour boiling water over the corn husks to soak. Use an inverted plate to keep the husks submerged for up to 1 hour.
4. Remove the finished chile from the cooking pot. It should be moist, not soupy. If necessary, transfer to a strainer to remove any excess liquid. Allow cooking pot to cool enough to handle and clean. Replace in the unit to steam tamales.
5. Prepare the masa: In a large bowl, using a hand mixer, mix together the masa, water, oil, baking powder and salt.
6. Assemble tamales: Drain and rinse corn husks and lay flat. Hold one in your hand and spread about ¼ cup of masa dough onto the husk. You want to cover 2/3 of the husk toward the wider end. Place about 2 to 4 tablespoons of chile on top of the masa (this will differ depending on the size of the corn husks). Fold the narrow end of the husk up into the tamale and then roll the sides together to enclose.
7. Repeat with remaining tamales.
8. Fill multicooker pot with 2 quarts of water and set the unit to Steam fitted with the steaming rack. Place 12 of the tamales onto the rack and set timer to 1½ hours. Check after 1 hour has passed – the husk should easily peel away from the side and the masa should be set. Repeat this step, making sure that there are 2 quarts of water in the cooking pot, and steam the remaining tamales.
*Masa harina is flour made from the dried corn dough used to make tortillas and can be found in speciality food stores or in the international aisle of most supermarkets.