Rinse rice and drain well. Use heavy kettle or double boiler. Add 1 cup water to rice and cook until water is absorbed. Gradually add milk, sugar, and salt. Cook over low heat approx. 1 hour or until rice is done. Stir gently to keep from sticking. Gradually stir a portion of the hot mixture into the following and add butter, beaten egg yolk and vanilla. Cook 1 minute longer. Remove from heat, pour into bowls, may garnish top with a little sugar and cinnamon mixture.