Before you give up on Starbuck's crumble cake have you contacted the corporate office? I love their maple scones and for awhile they weren't carrying them. A few of us contacted the office and they're now carrying them year 'round.
Earlez on Crenshaw in SLA is the only place where I've seen it served but that's not in the SFV. Theirs is the same as the coffee cake that used to be served in the LAUSD school cafeterias.
Crenshaw's a bit too far for me. How about the L.A. area? By the way, in New York they carry it at Cafe Europa. I'd sure like to taste it again here in town.