This chocolate frosting has melted chocolate in addition to cocoa powder to make it super chocolatey, also smooth with just the right about of sweetness.
(Yield: this will frost a 9-inch 2 layer cake)
540 grams dark chocolate bar (86% or as close as you can get)
1 cup (8 oz) heavy whipping cream, divided (or milk)
6 cups (750 grams) powdered sugar
1/2 cup (42 grams) unsweetened cocoa powder
2 cup (452 grams) salted butter, room temperature
1 tbsp vanilla
Finely chop chocolate bar and place in microwave safe bowl with 1/2 cup cream. Melt chocolate in short 5 second bursts in the microwave, stirring for 30 seconds before putting back into the microwave. Depending on your microwave, it should take 3 or 4 bursts. Don't burn the chocolate! Stir until smooth.
In bowl of stand mixer with paddle attachment, mix butter until smooth.
Add powdered sugar, cocoa powder and mix until smooth. Mix on low speed until well blended, then increase speed to medium and beat for 3 minutes.
Add vanilla and melted chocolate and beat on medium for 5 minutes until light and fluffy. If the frosting is too stiff add a splash of milk (half & half or heavy whipping cream).