Mom's (and Wilton's) Buttercream Frosting

This is my favorite cake frosting, hands-down. The only thing my mom (and now I) do different that the original Wilton recipe does not call for is to add a pinch of salt. Somehow it helps balance out the sweetness.

1/2 cup solid vegetable shortening, softened
1/2 cup (1 stick) softened butter (use real butter, even though it's more expensive)
1 t vanilla (and if you're making white frosting, you can get clear vanilla at Michael's or Hobby Lobby so your frosting will stay ultra white, and also sub more shortening for butter and add butter flavoring - see directions below).
4 cups powdered sugar
2 T milk (or maybe a little more until you reach a good consistency, just add one tablespoon at a time)
a pinch of salt

(Medium Consistency)
In large bowl, cream shortening and butter with electric mixer. Add vanilla. Gradually add sugar, one cup at a time, beating well on medium speed. Scrape sides and bottom of bowl often. When all sugar has been mixed in, icing will appear dry. Add milk and beat at medium speed until light and fluffy. Keep bowl covered with a damp cloth until ready to use.

For best results, keep icing bowl in refrigerator when not in use. Refrigerated in an airtight container, this icing can be stored 2 weeks. Rewhip before using.

For thin (spreading) consistency icing, add 2 tablespoons light corn syrup, water or milk.

For Pure White Icing (stiff consistency), omit butter; substitute an additional 1/2 cup shortening for butter and add 1/2 teaspoon No-Color Butter Flavor. Add up to 4 tablespoons light corn syrup, water or milk to thin for icing cakes.