In the meantime, make the filling. In a medium sauce pan add milk & whisk in flour. Cook on low heat, stirring constantly until mixture is thick. Remove from heat & allow to cool completely. (I put in refrigerator).
Cream together powdered sugar, crisco, & butter. Add to cooled flour mixture mix until well blended about 2 minuted on low speed.
(For cake pictured, I used chocolate icing to make a triple chocolate HoHo cake per my daughter's request.)