In large bowl, combine 1 cup shortening and 1 tablespoon vanilla. Beat with electric mixer on medium to high speed for 30 seconds. Slowly add 2 1/2 cups sifted powdered sugar, beating well. Add 2 tablespoons milk. Slowly beat in an additional 2 cups sifted powdered sugar. Beat in enough additional milk, 1 tablespoon at a time, until frosting is easy to spread.