Courtesy: McDonald's

by Patricia Sellers

Too often, the boss can’t relate to the workers on the front line.

Not so at McDonald’s .

McDonald’s U.S. president Jan Fields, who today announced plans to hire 50,000 new workers in a single day,  started behind the counter, cooking fries.

Her humble beginnings make her the most remarkable success on Fortune‘s Most Powerful Women list.

Before she started her career, cooking fries for $2.65 an hour, Fields grew up in Vincennes, Indiana, the seventh of eight kids educated in a four-room schoolhouse.

The tiny Catholic school, Old Cathedral, produced a couple of other corporate stars in addition to Fields. Her older brother, Jim Brocksmith, is a former deputy chairman and COO of accounting giant KPMG; he is on the boards of AAR and Sempra Energy . Former UPS CEO Mike Eskew, now a director of IBM , was schooled at Old Cathedral too.

Fields went on to a local community college, getting a job at McDonald’s to pay her way through school. While she dreamed of becoming a lawyer — vowing to quit her McJob each year — she soon got out of the kitchen and into management…and moved up so swiftly that she never had time to earn her college degree.

It all worked out. Fields, now 55 and No. 25 in Fortune‘s MPWomen rankings, oversees 14,000 U.S. McDonald’s restaurants with 650,000 workers. That number will rise to 700,000 come the big hiring day, set for April 19. Here’s Fields talking about her hiring blitz with CNNMoney’s Poppy Harlow: