Add butter (at room temperature, don't melt) and icing sugar to a large heatproof bowl. Then place the bowl in a shallow tub of warm water (kitchen sink works well).

Using a handheld mixer, beat until butter and icing sugar come together and form a thick paste. Remove bowl from the tub of water.

With your beater on slow speed, add the vanilla extract followed by the cream, making sure it's well incorporated and smooth.

Finally, beat on high speed for another 5 minutes, then it's ready to go!