Preheat your grill to 350F.

Roast the poblanos for 20-25 minutes, until the skins blister.

Remove from grill and place in a bowl and cover with plastic wrap.

Allow the peppers to sit 10-15 minutes and steam. This will make them easier to peel.

Remove the seeds and stems, and peel the skin off the peppers.

In a heavy bottom pot, add 1 T butter, the onion, and the poblano peppers (minus the reserved portion).

Cook 4-5 minutes over medium heat, until the onions are slightly translucent.

In a small bowl, mix 1/4 cup chicken broth with 1 T cornstarch, and set aside.

Add 1/2 cup chicken broth to the onion and poblano mixture, and mix.

Place the warm onion, poblano, broth mixture into a blender with the cilantro and buttermilk. Blend until smooth.

Return the mixture to the pot and add the remaining 1/2 cup broth, the cornstarch mixture and the reserved poblano peppers.

Bring to a simmer over medium heat, stirring constantly.

Cook until gravy thickens and then season with salt and white pepper, according to personal preference.

Enjoy warm!