In a bowl fitted with a paddle attachment, beat the butter on medium high until light and fluffy.
Heat the cream and chocolate chips in the microwave for about 30 seconds. Stir and heat again for 30 more seconds. Do this until you've made a silky, smooth ganache.
With the mixer on medium speed, gradually stream in the chocolate ganache. Scrape the sides of the bowl and mix again.
With the mixer on low speed, gradually add the powdered sugar. Beat on low speed for 1 minute.
Add vanilla and salt and beat until combined.
Turn the mixer to medium-high and beat for another 5 minutes.
Frost cake right away, or, if you cover and use later, make sure to mix with a rubber spatula right before applying to the cake to get rid of air bubbles.