Preheat oven to 350°. Coat a 13 x 9-inch baking dish with cooking spray.
Heat oil in a large skillet over medium heat. Add onion, poblano, and garlic; sauté 4 minutes or until onion and poblano are tender. Stir in chili powder, cumin, and oregano. Add stock, chipotles, and tomato sauce, and bring to a gentle simmer; cook 5 minutes or until slightly thickened.
Combine chicken and black beans in a medium bowl; add half of sauce mixture. Combine cheeses in a bowl; add 1/2 cup cheese mixture to chicken mixture. Toss to combine.
Place 8 tortillas on a microwave-safe plate; cover with a slightly damp paper towel. Microwave at HIGH for 45 seconds or until warm. Working with 1 tortilla at a time, place tortilla on a flat work surface; spoon 1/4 cup chicken mixture onto 1 end of tortilla. Roll up, jelly-roll style. Repeat procedure with remaining tortillas, heating up second batch of tortillas when first batch is used up. Arrange enchiladas, seam side down, in prepared dish. Pour remaining sauce over enchiladas; sprinkle with remaining cheese mixture. Bake, uncovered, at 350° for 30 minutes or until sauce is bubbly and cheese is melted and golden brown. Serve enchiladas with salsa, sour cream, and cilantro, if desired.