Think eggs, milk and butter are essential to scrumptious desserts? Hannah Kaminsky will try to convince you otherwise. Kaminsky, who is 19, recently published her first cookbook, “My Sweet Vegan,” which includes more than 70 recipes for goodies such as Root Beer Float Cupcake, Chai “Cheesecake” and Mocha Devastation Cake, for which she won a bake-off at the Dogwood Festival in Fairfield in 2006.