It's nothing but spuds--and we don't mean McKenzie. As a result of America's love affair with mashed potatoes, there's a growing interest in treating spuds as a bona-fide main course. Entrepreneur Brent McClun, for one, expects his Lawrence, Kansas-based chain of Potato Mountain cafes to have expanded to four locations by the time you read this. "Potatoes are a comfort food," says McClun, 37, explaining the enthusiastic reactions of patrons to the 100-plus varieties of mashed potatoes offered by the fledgling (and franchising) Potato Mountain. There are mashed potatoes with chicken, pineapple, broccoli--even pepperoni pizza. Raves McClun, "Potatoes are for everybody."