Roast the PoblanosPreheat the oven to 400°F (200°C). Lightly spray or brush the poblano peppers with oil and place them on a baking sheet. Roast for 20–25 minutes, turning occasionally, until the skins are charred and blistered.Pro Tip: Letting the peppers steam after roasting makes the skins easier to peel.
Steam and PeelTransfer the hot peppers to a covered container or a bowl with a lid and let them steam for 10 minutes. Peel off the skins, then carefully cut a slit down one side of each pepper and remove the seeds. Set aside.
Cook the ChickenSeason the chicken pieces with salt, pepper, and garlic powder. Heat a large skillet over medium heat, add a drizzle of oil, and cook the chicken until golden and fully cooked, about 5–6 minutes. Remove from the skillet and set aside.
Make the Creamy Chipotle SauceIn the same skillet, add chopped onion and cook for 2–3 minutes until softened. Add garlic and corn; cook for another minute. Stir in heavy cream, Mexican sour cream, chicken broth, and Oaxaca cheese. Cook over medium-low heat until the cheese melts and the sauce begins to thicken. Stir in chipotle sauce, season with salt and pepper, and simmer for 2–3 more minutes.
Stuff the Peppers & SimmerStuff each roasted poblano with a layer of cheddar cheese and the cooked chicken. Nestle the stuffed peppers into the skillet with the sauce, spooning sauce over the tops. Sprinkle with extra Oaxaca cheese, cover, and cook on low until the cheese melts, about 3–4 minutes.