In a medium bowl, combine powdered sugar and milk powder; stir with a wire whisk to blend.
With a pastry blender, cut in shortening.
Spoon about 1/3 cup of mixture into each of 8 small containers or ziplock bags and seal tightly. Label with date and contents. Store in a cool dry place. Use within 12 weeks.
Makes 8 packages Childrens White Frosting Mix.
To use: In a small bowl, combine 1 package frosting mix and 3/4 teaspoon water. Stir well with a spoon until smooth and creamy. Makes about 1/4 cup frosting. A drop or two of vanilla may be added if desired.