With your whisk attachment on your mixer, whisk your butter until it is creamy, scraping down as necessary.

Whisk in the cocoa powder and then the first cup of powdered sugar. Scrape down the sides, continue mixing and add the second cup of powdered sugar. Add cups three and four and scrap down again.

Continue mixing and add the buttermilk, turning your mixer to medium high until the frosting is creamy. With the mixer stopped, add the red food coloring, and mix until it is fully combined.

Store in an airtight container in the refrigerator, up to three days. Bring the frosting to room temperature before pipping or spreading.