Meanwhile, place poblano peppers directly on a burner over a medium-low gas flame. Turn regularly with tongs to blacken skin, 10–15 minutes (if you don't have a gas stove, you can blacken peppers on a sheet pan under a broiler, turning regularly, about 15 minutes). Place peppers in a paper bag; seal and let sit (and steam) until cool enough to handle. Peel peppers, removing as much of the charred skin as possible without rinsing. Seed and coarsely chop. Transfer to a small bowl and toss with scallions and cilantro.
Preheat oven to 375°. In the bottom of a 1- to 1 1/2-quart soufflé or baking dish, spread half of bean mixture. Top with half of cheese, crumbled, and half of pepper mixture. Repeat layering once more, ending on pepper mixture. Place dish on a sheet pan and bake 30–35 minutes, until top is bubbling. Meanwhile, arrange tortilla wedges on a large baking sheet in a single layer. Place in oven with dip and bake 10–12 minutes or until crisp. Brush with oil and sprinkle with salt, if desired. Serve hot with tortilla chips on the side.