Equal parts butter and cream cheese(or change the ratio to suit your own taste)
healthy pinch of salt
splash of vanilla
powdered sugar
add-ins: lemon zest, orange zest, crystallized ginger--whatever sounds good
Thin with: lemon juice, orange juice, half and half or milk to spreading consistency or use more to make a glorious glaze for pound cake or cinnamon buns.
Instructions
You can make this by hand, but it's way easier with a stand mixer. Plop the room temperature butter and cream cheese in the mixer and mix on medium low until smooth.
Add in the salt and vanilla and whip until fluffy.
Add in powdered sugar on low speed, a bit at a time, until the frosting is as sweet as you like it. I use about 1 pound of powdered sugar to 4 oz. each of butter and cream cheese, but it is entirely up to you and your taste buds.
Add in your zests or anything else you might be using and continue to beat until light and fluffy. You shouldn't need any liquid if you're icing a cake, but it is to your taste--if you don't want the icing so thick, add some liquid, a little at a time.
Now, take the bowl and a spoon, sit on the couch and have at it. Um, I mean, go ahead and frost your cake, or glaze your cinnamon rolls.