Stir the yogurt, honey and vanilla together in a bowl until smooth.
Spoon 60 ml (a quarter cup) of yogurt into the bottom of each clear cup.
Transfer the remaining yogurt into a piping bag or a zip-lock bag with a small corner snipped off.
Pipe a rounded ghost head with a slight peaked top onto the yogurt in each cup, using about 2 tablespoons of mixture per cup.
Press 2 blueberries side by side into the piped ghost face for eyes, and 1 blueberry below for the mouth.
Refrigerate cups for at least 15 minutes so the ghost holds its shape before serving.