Set mixer to medium-high speed and beat butter and cream cheese for 2-3 minutes.
Stop beating momentarily - have a sip of your favorite drink - then add 1 cup granulated sugar and 1 cup light brown sugar,
then vanilla. I used both a hand blender
and a whisk-attached drill to mix until smooth
then, taste it - very important. If you feel the taste and texture suits you, then you're ready to top it to your cake. Or maybe refrigerate or freeze for later use.
Or just pour it simply on a piece of carrot cake and Enjoy!