Chris Sommers and Frank Uible have had quite a ride since opening the original Pi two and a half years ago: a trip to the White House to cook for the restaurant's highest-profile fan, Barack Obama; new locations in Kirkwood, the Central West End and Chesterfield; a food truck, nicknamed Pi on the Spot, to capitalize on Pi's popularity and the nation's hottest restaurant trend. If success and expansion have changed Pi, then it's only for the better. The pizzeria's signature cornmeal-based deep-dish crust remains fantastic, while each location has introduced new variations, like the Central West End's "Mission," with sausage and anchovies; and Kirkwood's "the Kirkwood," with beef-and-pork meatballs. Variation is the key term, though. The theme — and the quality — is consistent, ensuring that however much farther Pi's reach extends, great thick-crust pizza will remain within our grasp.