Kristin Cantwell, the solo performer in the cabaret show Butter: A Love Story, proves an affable host for the evening. Taking on the persona of a Paula-Deen-heavy amalgam of Food Network personality types, she introduces us to the wonders of the butter bacon burger, the importance of creating a mood with “roombiance,” and the assets of Taylor the Latte Boy, who services her at Starbucks. If only the girl could sing. Cantwell has assembled an…