Add the room temperature butter to the stand mixer and mix until lighter in color and completely smooth.
Add in four cups of powdered sugar. Use the rubber spatula to mix the powdered sugar into the creamed butter, then cover with a towel and mix with the stand mixer.
Add one and a half teaspoons of vanilla extract and one half teaspoon of LorAnn Super Strength Coffee Oil into the mixer and mix until incorporated.
Sample the buttercream at this point to check consistency and flavor.
If the coffee flavor is just right or too strong, add in 1-2 tablespoons of room temperature milk. The amount of milk will depend on how much thinner you would like the buttercream consistency to be while piping.If the coffee flavor could be a bit stronger, add in 1-2 tablespoons of room temperature cold brew coffee (or regular brew or espresso). The amount of coffee will again depend on your preferred buttercream consistency. Mix all of the liquids into the buttercream, scraping the sides of the bowl to bring it all together.
If using gel food coloring, add the color into the buttercream. Otherwise, add the coffee buttercream into prepared icing bags and decorate your cookies.