Grill or broil the poblano peppers until skin is charred, place in a glass bowl and cover tightly with plastic wrap, set aside for five minutes.
While the peppers are set aside, melt the butter over medium-high heat, whisk in flour and continue to stir for a few minutes to remove the flour taste. Whisk the half & half in slowly. Whisk the cheese in until melted and the mixture is thickened, add the chicken broth. Stir or whisk to thoroughly combine.
Turn heat to medium-low. Remove the poblanos from the bowl, peel the skins under running water; slice, seed and finely chop. Seed and chop the serrano or jalapeno. Rinse, dry and finely chop the roasted red pepper. Add all to the soup.
Drain and rinse the black beans, add them along with the chicken, corn and all seasonings to the soup. Stir well, simmer over low heat for 20-30 minutes to heat through and allow flavors to combine.