12ouncessemi-sweet chocolate, coarsely chopped (my favorite is linked in the notes below)
1cupunsalted butter, room temperature
1 1/2cuppowdered sugar, sifted
2teaspoonsvanilla extract
1/4teaspoonsalt
1/2cupheavy whipping cream, room temperature
Instructions
In a heatproof bowl set over a pot of gently simmering water (make sure the bottom of the bowl does not touch the water), add the chocolate. Allow chocolate to sit undisturbed for about 4 to 5 minutes. Stir until melted and smooth. Remove from the stove and allow to cool until nearly room temperature.
In the bowl of a stand mixer fitted with the paddle attachment, cream together the butter and sugar on medium speed until pale and fluffy.
Scrape down the sides of the bowl and add the extract, salt, and about 1/3 of the cream. Mix on low-medium speed until just combined.
Scrape down the sides of the bowl and add half of the remaining cream. Continue to mix on low-medium speed until combined.
Remove the bowl from the mixer and add the cooled chocolate into the center of the butter and sugar mixture, trying to avoid any chocolate contact with the sides of the bowl. Fold in by hand until mostly combined, trying to prevent melted chocolate from touching the sides of the bowl.
Stir in the remaining cream by hand until combined. Return bowl to the stand mixer and mix on low-medium until smooth and fluffy, about 30 seconds. Use immediately.