Preheat broiler to high.

With the oven door ajar to allow steam to escape, broil the poblanos until charred all over. Place chilies in a bowl, cover with plastic wrap and let cool. Peel, seed and roughly chop.

Melt butter in a large, skillet over medium-high heat. Add onions, garlic and cumin, and season with salt and pepper. Cook until onions are translucent, 8-10 minutes.

Add poblanos, then whisk in flour and cook for 1-2 minutes. Add stock and let thicken.

Transfer to a food processor, add cilantro and purée. Transfer to a pot, add cream and let thicken to coat a spoon.

Freeze flat in a gallon-size bag or in small sandwich-size bags for smaller servings.

Serve over chicken, pork or steak.