A glossy, smooth drip made with candy melts and hot water. Works in any color: white, pink, red, blue, green, or whatever shade of candy melt you start with. See the notes section for the gold variation.
Heat the water in a microwave-safe bowl for about 30 seconds, until hot but not boiling.
Microwave the candy melts for about 1 minute on full power just to begin the softening process.
Pour the hot water over the candy melts or chopped chocolate. Let sit for 1 to 5 minutes without stirring. (Alternatively: microwave the water and candy melts together for 30 seconds, then stir.)
Whisk gently until smooth. If chunks remain, microwave another 15 to 30 seconds and whisk again.
Cool for 1 to 2 minutes until warm but not hot (about 90°F). Test the consistency by piping a drop down a cold drinking glass; it should set within a few seconds.
Spoon the cooled ganache into a piping bag, snip a small hole at the tip, and the drip is ready to pipe onto a chilled cake.
Video
Notes
Color options
Use colored candy melts (pink, red, blue, etc.) for the easiest custom color.
For a custom shade, tint white candy melts with food coloring and a touch of white food coloring to make it less transparent.
Gold (or other metallic) finish variation
Mix 2 teaspoons edible gold luster dust with ¼ teaspoon neutral oil into a thick paste.
Place a piping bag in a tall cup, fold the edges down, and use a small paintbrush to coat the inside bottom of the bag with a thick layer of paste, about 2 to 3 inches up from the tip. For a heavier metallic look, double-coat.
Carefully fill the bag with cooled white water ganache without disturbing the dust coating. Pipe as normal. The same technique works for silver, rose gold, copper, or bronze dust.
Make-ahead and storage
The ganache is best used within 30 minutes of making it. If it sets too soon, microwave in 5 to 10-second bursts and whisk smooth.
Once piped onto a cake, drips set within a few minutes at room temperature.
Critical do-nots
Don't substitute chocolate chips for the candy melts or chopped chocolate; the stabilizers prevent clean melting.
Don't use olive oil or coconut oil for the metallic paste; they carry flavor through to the finished drip.
Don't apply to a warm cake. Always pipe onto a chilled cake.