Add heavy cream to mixing bowl, mix starting with low speed, then gradually increase to medium speed until the cream starts getting thicker (the gradual speed progression prevents you from spraying yourself with cream).
When the cream starts to thicken stop the mixer, add in the powdered sugar and then resume mixing again starting with low speed and increase to medium speed up to high speed.
The cream will thicken and start to peak. Stop the mixer and add in the peppermint extract. Mix on high speed until the cream is thick and stiff.