Place potatoes and parsnips in a large pot, cover with water, and add one tablespoon salt. Bring to a simmer and cook for 20-25 minutes, or until potatoes are very tender. Drain, return to pot, and mash until almost smooth (or leave slightly chunky, if you prefer). Heat milk with six tablespoons of the butter until scalding and then add in slowly, mashing or stirring into potatoes until smooth. Season with pepper. Dot with remaining butter.

Courtesy of Whole Foods Market.