Using the best chocolate and ice cream you can find ensures a super rich shake. You won't want more than a small glass!
Place half-and-half and chocolate in a microwave-safe bowl and zap to melt, about 30 seconds. Whisk until smooth, then chill until no longer warm, about 20 minutes, whisking occasionally.
Scoop ice cream into a blender or food processor. Add chocolate mixture. Blend until smooth. Pour into 2 glasses. Slurp.