Coach stands behind catcher and simulates bunt by rolling ball down first or third baselines or directly in front of catcher.
For right handed catcher make sure for bunt down third baseline that ball is fielded with back to pitchers mound. Catcher "scoops" ball into glove with both hands then rotates and throws to first using a good crow hop. Bunts in front of plate or down first baseline are fielded with left shoulder facing first base. Again scooping ball and using crow hop.
An added variety to this drill has the coach calling the base to which the catcher is to throw. This makes the catcher react to the call.