Line a baking sheet with parchment paper. Make sure the strawberries are completely dry — any water will seize the chocolate.
Combine the white chocolate chips and coconut oil in a heatproof bowl set over simmering water (or microwave in 30-second bursts), stirring until completely smooth.
Hold each strawberry by its green leaves and dip it fully into the white chocolate, turning to coat. Let the excess drip back into the bowl, then set it upright on the parchment.
Refrigerate 10 minutes until the coating is set.
Melt the semi-sweet chocolate chips. Dip a toothpick or use a small piping bag to draw two eyes and a spooky "O" mouth on each ghost.
Chill 5 more minutes to set the faces. Serve the same day for the freshest berries.