1. In a small saucepan, warm cream over medium-high heat until tiny bubbles form around edge of pan. Remove from heat, add chocolate chips, and stir until melted and smooth. Scrape chocolate cream into a medium bowl, cover, and refrigerate until thickened, about 1 hour.
2. Using a heavy-duty mixer, beat chocolate cream until fluffy. Spread about 1 tablespoon over each of 20 cookies. Sandwich with another cookie.