Mile High Frosting

Slowly add milk to flour and salt in small saucepan to make a smooth paste.

Medium heat, stirring constantly, until thick.

Cool completely (may be refrigerated). If mixture becomes lumpy, beat until smooth.

In small bowl of electric mixer, sugar, shortening and margarine until fluffy.

With mixer running at slow speed, add flour mixture a tablespoon at a time.

Add vanilla beat at high speed until stiff and fluffy.