Combine pudding mix and sugar in a small, heavy saucepan; gradually add milk. Bring to boil over medium heat, stirring constantly. Remove from heat; add butter, rice, coconut, vanilla, then egg yolks. Cool to lukewarm.
Beat egg whites until stiff peaks form. Fold into cooled pudding. Pour into 1½-qt. soufflé dish or straight-sided casserole. Bake in moderate oven