Double the recipe to frost a 6" or 8" cake.
In a stand mixer bowl, add the room temperature butter and cream cheese. Mix on medium-high until the butter and cream cheese is light in color and fluffy. Stop the mixer every few minutes to scrape down the sides of the bowl to make sure all the butter and cream cheese is well blended. This step can take up to 5 minutes and is essential to whipping air into the butter and cream cheese, so your buttercream will be smooth and creamy.
Once the butter and cream cheese is light in color and fluffy, continue to mix on medium and add the vanilla extract, salt, and cinnamon. Scrape down the sides of the bowl again before moving to the next step.
Then gradually add half of the sifted powdered sugar to the butter mixture. Next, add 1 ½ Tablespoon of the heavy cream. Scrape down the sides of the bowl and especially the center of the bowl to make sure all the powdered sugar is getting incorporated.
Finally, add the last half of the powdered sugar and mix on medium-high. Carefully add a few drops of pink food coloring to the buttercream to get a light pink color. Continue to mix and scrape down the sides of the bowl until you don't see any more powdered sugar. If the buttercream is a little stiff, then mix an additional ½ tablespoon of heavy cream. Continue to mix until you have a creamy and smooth buttercream.
The cinnamon buttercream is ready to use. Fill a pastry (piping) bag with the buttercream or use an offset spatula to frost the cake.
Double cinnamon buttercream recipe to easily frost a 6" or 8" layered cake.
For later use store in airtight containers and store in the refrigerator for up to 2 weeks. When you’re ready to use the cinnamon buttercream, place it on the counter to come back up to room temperature. Then mix it on medium-high to make it smooth and creamy once again.