LuAnn's Vanilla Cream Puff Filling

1/2 C. white sugar
1/2 C. flour
1/4 tsp. salt
1 1/2 C. milk
1 egg, slightly beaten
1 Tbs. butter
1/2 tsp. vanilla

Combine sugar, flour and salt in saucepan.  Mix well.  Add milk, mix till smooth.  Cook over medium heat till thickened stiring constantly. remove from heat.  In small bowl with egg add small amount (about 1 Tbs) of mixture at a time.  Then stir egg mixture into saucepan. Cook 1 minute more.  Remove from heat.  Add butter and vanilla.  cool in refrigerator.  Put plastic wrap on pudding to prevent a skin.                                                                                                   Makes 11/4 C. filling.