Cook the jalapeños under the broiler, turning once, until blackened, about 10 minutes. Once cool, leave on the charred skin, remove the stem and seeds and finely dice.

In a large skillet, sauté the bacon on medium heat until crisp and the fat has been rendered, about 5 minutes. Remove bacon from skillet and place on paper-towel-lined plate.

Pour 1 tablespoon of the bacon grease into a large pot, reserving the rest for another use. (Leftover bacon grease will keep in the refrigerator for up to six months.) Add the celery and onions to the pot. While stirring occasionally, cook on low heat until soft—about 8 minutes. Add the garlic and cook for 30 more seconds.

Add the chicken broth, potatoes, cumin and cayenne. Turn up the heat to high and bring to a boil, then turn the heat to low and simmer uncovered for 30 minutes or until the potatoes are fork tender.

Turn off the heat and let the soup cool for 10 minutes, then pour into a blender and puree. (You may have to do this in batches. Alternatively, you can use a stick blender in the pot).

Return the soup to the pot and stir in the diced jalapeños, cooked bacon, cilantro, buttermilk and half and half. (This is a thick soup, so if you prefer it thinner, add water, more broth, more buttermilk or half and half.) Turn the heat to low and cook for 5 minutes. Adjust seasonings and add salt and black pepper to taste.

Serve topped with sour cream and shredded cheese.