Cupcakes are the passion at Sweet Cupcakes, a Boston-based boutique cupcakery cited as serving up ''Boston's Best Cupcakes 2009'' by The Improper Bostonian . . . and not without reason. Its cupcakes are like little pieces of heaven with delicious dollops of frosting, fillings, and a variety of flavors, from cappuccino to pumpkin ginger. Now The Sweet Little Book of Cupcakes reveals Sweet's secrets, from baking techniques and decorating tips to recipes for cakes, frostings, fillings, drizzles, and toppings!