Lightly saute onions in butter until soft. Add chili powder, cumin, corn and red pepper. Stir for 1 minute. Add broth, tomatoes and poblanos. Bring to a boil, then remove from heat. Mix cream cheese until smooth, then slowly add a little of the hot soup to the cream cheese, stirring as it is absorbed. Repeat until the cream cheese is a sauce consistency. Add this cream cheese to the hot soup and stir well to combine. Heat until tiny bubbles form around the edge of the pot. Serve immediately, topped with cilantro.