It’s a sad but pretty well-established fact that a good slice is hard to find. Maybe that’s why the recent opening of Artichoke Basille’s Pizza, an unassuming little storefront hard by Stuyvesant Town, has stirred up such febrile excitement on food blogs and in the persons of practically drooling, slightly dazed customers (the Underground Gourmet included). First came the comparisons to the great Brooklyn slice joint Di Fara, on sliceny.com. Then came Keith Richards: “He got a regular slice, and I gave him a piece of spinach-and-artichoke to sample,” says Artichoke co-owner Francis Garcia. “He started doing something with his hands. Playing air guitar and jumping around; it was cool.” If that wasn’t enough of an endorsement, what followed was the culinary equivalent of a papal blessing— a visit from Dave “Momofuku” Chang, who, unlike Keith Richards, did not jump around or play air guitar but, according to a blogger on line behind him, tootled off with three pies.