Mix margarine and sugar, then add egg and then dry ingredients. Divide in three and press into greased pie dishes. Prick bases then bake at 180 C for 10 - 15 minutes, or till golden brown. Cool. Boil milk and vanilla. Beat eggs and sugar with flour and corn flour. When milk is boiling rapidly, add egg mixture. Cook till sauce thickens. Pour into pie shells, sprinkle with cinnamon and cool. (More corn flour is sometimes necessary.)