Last night, DCist was invited to participate in one of EatBar’s cocktail classes, taught by Gina Chersevani. The theme for the evening was “Witches’ Brew, Contorted Concoctions,” which took imbibers on a tour of some molecular mixology techniques. Some elements were basic, while others required some special equipment and chemicals. The class also included some small nibbles to match the cocktails. The highlights of the evening included “popcorn” made by freezing whipped cream made from…