Over medium heat in a sauce pan cook the butter and Onion until translucent. Then remove from the heat and set aside for a few minutes to cool
Add to the Sauce pan the Mexican Creme, Poblanos, Serrano, Cilantro, Chicken Stock and the Avocados. Use an immersion blender to puree into a smooth sauce
Roasted Poblano
Preheat the Broiler.
Place the Poblanos on a baking pan lined with foil
Place as close to the heat as possible and roast them for 5-7 minutes per side until the entire chilie is charred
Move the charred chilies to a ziplock bag for about 10-20 minutes to allow them steam.
The skin should now easily be removed.