Char the poblano peppers on top of a gas burner, on a grill, or under the broiler) until all of the sides are blackened. Place in a bowl covered tightly with plastic wrap, allowing the steam to help loosen the skin. With your fingers or a spoon, scrape and discard the blackened skin then remove the seeds and core. Coarsely chop the poblanos, and place into a mini food processor. Add the Parmesan, cilantro, garlic, chili powder and oil and process until well combined, but not totally smooth. Taste and season with salt.