1/4 cup shortening
1/4 cup butter, softened
1/2 tsp clear vanilla extract
2 cups confectioner's sugar, sifted
1 tbsp. milk
*my modifications: I ended up using less than 2 cups of sugar, 3 tbsp. of milk and 1 tbsp. light corn syrup.
In large bowl, cream shortening and butter with electric mixer. Add vanilla. Gradually add in the sifted sugar, beating well on medium speed. Scrape sides and bottom of bowl often. When all sugar has been mixed in, icing will appear dry. So add the milk and then beat at medium speed until light and fluffy. Keep bowl covered with a damp cloth until ready to use.
Storing: Keep icing bowl in an airtight container and in the refrigerator when not in use. It can be stored up to 2 weeks. Rewhip before using.