Step 1

In a the bowl of an electric stand mixer, fitted with paddle attachment, whip butter on moderately high speed until very pale and fluffy (nearly white in color), about 5 - 8 minutes, occasionally scraping down sides of the bowl.

Step 2

Sift in cocoa powder then add in powdered sugar, 3 Tbsp heavy cream and vanilla and mix on low speed until combine, scrapping down the sides of the bowl as needed and adding up to 1 tbsp additional cream to thin if desired.

Step 3

For added fluffiness if desired continue to whip about 3 - 4 minutes longer.