Microwave for 20 second intervals, stirring in between each interval, until all the chocolate is melted.
Once melted, let sit for 15-30 minutes, until it reaches 85-95 ℉.
Either pour over cake, spreading towards the outside of the cake so it drips or add to a pastry or plastic bag with a medium trip and drip around the edges, then fill in the center and smooth with a spatula.
Put back in the fridge to chill until ready to finish decorating.
Notes
Chop all of the chocolate into small pieces. If you don’t, it can sometimes take awhile to make sure it gets fully melted and incorporated into the cream. If you have pieces of unmelted chocolate, you can use a plastic spatula to press against the side of bowl to break it down. Then, reheat until it’s all combined. You can also use a regular or immersion blender to mix if there are pieces of unmelted chocolate. Then reheat for 10-15 seconds until smooth..
Be patient when letting the chocolate cool. It takes longer than you think, normally between 15-30 minutes to cool down to the right temperature.
Use a candy or instant read thermometer - this is key to getting the chocolate the right temperature. You want it between 85-95 degrees Fahrenheit.
Make sure the cake is cold. Keep it in the fridge and take it out right before you are going to add the drip. This helps slow the drip falling down the side of the cake.
To get the drips exactly how you want them, put the chocolate use a pastry or plastic bag with a medium size tip and drip around the edges of the cake, and then fill in the top.