**I like to chill my cakes before pouring ganache over the top, so if you'd like to try this, just remember to put your cake in the refrigerator for about half an hour.
Place chocolate chips in a heatproof bowl. Heat cream in a small saucepan over medium low heat until it's barely simmering. Pour cream over chocolate chips. Let the cream sit for 5 minutes, then stir until smooth.
You can pop it in the microwave for 5-10 seconds if there are still noticeable chocolate lumps. No one likes lumpy ganache. ;)
Pour about a cup of ganache on top of the cake and use an offset spatula or knife to smooth it out to the edges. Add more closer to the edges if you need to coax it over the sides. (It's easier to start out with a little and add more if you need it.) Then, if you'd like, transfer remaining ganache to a piping bag or Ziploc bag with a tip cut off. Add extra chocolate drips by placing the tip just over the top edge of the cake, piping a small bit of ganache, and let it fall down the sides.