When it comes to offering guests something sweet at the end of a meal, you don’t have to reinvent the wheel. But a little tinkering with the classics — a bit of anise in the hot chocolate or some candied pistachios in the carrot cake — helps keep customers engaged, chefs say. Michael Paley, chef of Proof on Main, said that over the summer the Louisville, Ky., restaurant featured a gelato cart that offered such flavor options as lavender, raspberry, strawberry and