Boo-Nilla Shake
To decorate the cups
For 12 faces, place 1/3 cup (2 ounces) semisweet chocolate chips in a microwave-safe bowl; microwave on high until melted, 1 to 1 1/2 minutes; stir. Using a small brush, paint chocolate inside glasses (if it hardens too soon, microwave 20 seconds more). Let set a few minutes before adding shake. Prepare glasses up to a day ahead, but don't fill until ready to serve.
Boo-Nilla shake recipe