Using a standing or handheld electric mixer, beat butter and cream cheese together until well combined.
Slowly add the icing sugar (1/2 cup at a time) with the mixer set to low speed. Continue to whisk on medium-high for another 2-3 minutes or until the mixture is thick and creamy.
Decorate your cake/cupcakes!
Notes
Sofia's Tips:
For a lump free frosting:
1. Don’t forget to have the cream cheese and butter at room temperature (remove from the fridge at least 2h before starting the frosting)
2. Sift the icing sugar (similar to cocoa powder, I find that icing sugar often has quite a few lumps which can have difficulty dissolving in the frosting without a good sifting!)
In the event that your frosting ever becomes too thick (a rare occurance), you can always add a teaspoon of milk/heavy cream at a time and continue to whisk on medium-high until it thins out to the perfect pipe-able consistency. Similarly, if your icing is to loose - just add a bit more icing sugar!