1. In bowl of a standing mixer, whisk heavy cream, sour cream, brown sugar and salt until combined. Cover with plastic wrap and refrigerate at least four hours (or up to 24 hrs) stirring occasionally to ensure that the sugar dissolves. (It takes a while for brown sugar to dissolve.)

2. When ready to serve, add bourbon and beat mixture at medium speed until small bubbles form around edges, about 40 seconds. Increase speed to high and beat until fluffy, about 1 minute longer. Serve immediately.