Adapted from tasteofhome.com
cup butter softened
cup firmly packed light brown sugar
cup whole milk divided
cups confectioners sugar divided
teaspoon of salt
In a medium bowl , beat butter and brown sugar at medium speed with a mixer creamy. Add two tablespoons of milk and gradually beat in one cup of confectioners sugar. Add remaining two tablespoons of milk and remaining cup of confectioners sugar. Stir in vanilla. and salt . Use immediately.