On its 15th birthday, Bjorn Shen’s cult dining spot has swapped falafel for pies. The chef’s fighter mentality – and lifelong love of pizza – fuels the restaurant’s bold new chapter. After 15 years of hummus, falafels and bold Middle Eastern plates, Bjorn Shen finally admits: He was bored. “I mean, how many creative versions of hummus can I do? How many more things can I put shawarma on?” the chef-owner of Artichoke quipped. “And besides, I don’t have a grandmother in the Middle East.”  His