A former graphic designer for the Gap, Marshall Cannon is now a professional pieman.Marshall Cannon, 39, didn’t grow up baking with his grandmother, and he’s never worked as a pastry chef. A former graphic designer for the Gap, this now-professional pieman is pure self-taught talent, motivated only by a “huge sweet tooth.” His success has followed his practice of hand-rolling each all-butter crust for each small pie. As for fillings? The Hayes Valley resident, who commutes to a commercial kitchen in San Jose, keeps to the classics: lemon meringue, strawberry-rhubarb with a crumble top (our personal favorite), apple and sweet potato.