Bittersweet Café Chocolatier Seneca Klassen to Present a "Chocolate Evening" of Botany and Chocolate History at SF Conservatory of Flowers September 17 SAN FRANCISCO, CA--(Marketwire - September 2, 2009) - Seneca Klassen, chocolatier for the Bay Area's three renowned Bittersweet Cafes, will share a mouth-watering evening discussing chocolate at the...