If needed, remove the butter from the refrigerator and allow it to come to room temperature.
Once the butter is at room temperature, mix it on high speed in a stand mixer using the paddle attachment until light and fluffy.
Slowly add in four cups of powdered sugar, mixing on low speed, until fully incorporated. Do not mix higher than low speed, as this will incorporate air bubbles.
Add the vanilla and almond extract and mix until combined on low speed.
Add in two tablespoons of milk and mix on low speed. If the buttercream is too thick, add up to two more tablespoons of milk.