My sister Rachel is quite the mashed potatoes connoisseur, so her pronouncement that my Thanksgiving mashers were the best she's ever had put me on a tater high. When my CSA left me with an abundance of sweet potatoes, they were just calling to be mashed too.
My favorite sweet potatoes are the soft, silky ones that have been roasted on hot coals—I thought that was a good place to start with these. After an hour nestled in the embers, the potatoes were so soft, they could be easily scooped out with a spoon, requiring no further mashing. I only added butter, half and half, a little brown sugar, salt, and pepper. They were ready to go.
Not quite the achievement of my Thanksgiving mashed potatoes, these were still mighty fine—soft and creamy, with a sweetness that wasn't sickening, but enough to feel like a holiday indulgence.
Light one chimney full of charcoal. When all charcoal is lit and covered with gray ash, pour out and spread coals evenly over entire surface of coal grate. Wrap each sweet potato in aluminum foil and set in coals. Using tongs, move any loose coals around or on top of potatoes. Roast sweet potatoes until they are completely soft and a paring knife can be inserted with no resistance, 40-60 minutes, turning four times during cooking to ensure even roasting. Remove potatoes from coals and let sit until cool enough to handle, 10 to 15 minutes.
Unwrap potatoes and split in half. Using spoon, scoop out flesh into small sauce pan. Mix in melted butter and brown sugar. Add half-and-half 1/4 cup at a time until potatoes are at a desired consistency. Season with salt and pepper to taste and serve.