Preheat the broiler. Lay the poblano peppers on a foil-lined baking sheet in a single layer. Place the pan under the broiler and broil until most of the skin is black. Flip the chilies over and repeat on the other side. It will take between 4-6 minutes per side. Alternatively you can char them over an open flame on the stove-top.
Carefully remove the poblano peppers from the sheet pan. Place the roasted chilies into a large Ziploc bag or place in a bowl covered with plastic wrap. Let them rest for 15-20 minutes until soft and pliable. Then peel off the skin, remove the seeds, and slice. For a spicier dish, leave in some of the seeds.
Meanwhile, add the oil to a pot or skillet. Add the sliced onions and cook for 8-10 minutes until they began to become translucent. Add the corn and roasted poblano peppers cook for an additional 5 minutes.
Stir in the sour cream, chicken bouillon, cheese, and milk. Turn off the heat and continue to stir until everything is melted and creamy. Taste and season if needed. Serve in tortillas, with chips, or over rice.