5 Tbsp flour
1 c milk
1/2 c butter
1/2 c shortening
3/4 c sugar
Whisk flour and milk slowly over low heat until blended and thick. Remove from heat and allow to cool. Cream butter, shortening, and sugar. Mix all ingredients together. Use large decorator tip and icing bag to shoot filling to cooled cupcakes.
Refrigerate any remaining cream.
Source: Kathy Winn (submitted by Pamela Peterson)