Preheat your oven to 350 degrees Fahrenheit. Spray a 9 by 13 inch baking dish with cooking spray.
Place all of the peppers in a large bowl and cover with a plate. Microwave for 6 minutes. This will soften the peppers which will allow for a shorter baking time.
4 bell peppers
In a large skillet over medium heat, melt the butter. Sauté the onion, jalapeño, and garlic. Season with cumin, oregano, salt, and pepper. Cook until the onions are translucent, about 5-7 minutes.
2 tablespoons unsalted butter, 1 small yellow onion, 1 jalapeño, 2 garlic cloves, 2 teaspoons cumin, 2 teaspoons oregano, 3/4 teaspoon kosher salt, dash of black pepper
Whisk in the flour until the veggies are completely coated and there are no streaks of white. Slowly whisk in the chicken stock, a few tablespoons at a time, waiting until it has been absorbed to whisk in more. While you should work slowly here, this process doesn't need to take more than 1-2 minutes.
2 tablespoons all purpose flour, 1 cup chicken stock
Stir in the chicken, beans, green chiles, and 1 cup of cheese. Taste the sauce and add more salt and pepper if necessary.
2 cups shredded chicken, 15 ounces Northern beans, 4 ounces green chiles
Place the microwaved peppers cut side up in the prepared baking dish. Divide the chicken mixture among the peppers. Top with the remaining 1 cup of cheese. Bake for 25 minutes then broil for 1 to 2 minutes, or until desired browning has occurred.