1. Follow directions to make your favorite cupcakes.
2. Use an electric mixer with a paddle attachment to blend shortening and butter on medium speed for 2 minutes; using a rubber spatula, scrape down sides and bottom of bowl and mixer paddle.
3. Gradually add confectioner's sugar, 1/2 cup at a time, mixing on low speed first and then medium speed; scrape down sides and bottom of bowl and mixer paddle after each addition.
4. Add vanilla; mix on medium speed for 1 minute; scrape down sides and bottom of bowl and mixer paddle.
5. Add milk; mix on medium speed for 1 minute.
6. Frost cupcakes immediately or store icing in refrigerator in an airtight container; decorate cupcakes as desired.