1/2 c. butter
1/2 c. vegetable shortening
1 tsp. vanilla
1/8 tsp. salt
4 c. powdered sugar
3 tbsp. milk

Cream butter and shortening together. Add vanilla and salt. Beat in sugar, one cup at a time. Scrape sides and bottom of bowl often to make sure sugar is well blended. Add milk and beat at high speed until light and fluffy. Keep frosting covered in the refrigerator when not in use.