Grate or cut chocolate into 2 cups milk, place over hot water to melt. Combine first 4 ingredients and blend with 1/2 cup milk. When chocolate is melted and milk is scalded, add to egg yolks well beaten. Stir constantly. Add flour and sugar mixture. Cook over boiling water stirring constantly until thick, add vanilla. Cool. Place in pastry shell.
Beat egg whites until stiff then add sugar gradually. Spread on pie. Bake in oven at 300 degrees for 7 minutes.
