3 1/2 cups powdered sugar
1/2 tsp milk
1/2 tsp vanilla
1/8 tsp salt
Beat butter and salt on medium speed until light and fluffy, about 2 minutes. Reduce the speed to low, gradually add the confectioner's sugar and beat until incorporated. Add the vanilla and milk and beat until smooth and creamy. Do not over mix. Add additional milk, 1 tsp at a time, if frosting is not spreadable.