Place potatoes in stockpot, add water to cover, cook until tender. Drain water, return potatoes to stockpot. Cut the potatoes in four, transfer to a bowl and slightly mash with spoon (big chunks). Add buttermilk, chipotle sauce, salt and pepper. Fold ingredients together to combine. Cook until completely heated through. Return to pan and heat covered when ready to serve, or place in the oven, covered, at 250° for 15 minutes.
When you mix your potatoes, mix them as little as possible ? the more you mix them the stickier they will become.
Chipotle peppers in adobo sauce can be found in the Hispanic section or the canned chile pepper section of the grocery store.
For chaffing dish service - for moister potatoes, add more buttermilk or chicken stock.