In small bowl, stir powdered sugar, 1/4 teaspoon vanilla and 3 teaspoons of the milk, adding more milk by teaspoonfuls, until spreadable. Spread glaze over bread. Sprinkle with additional cinnamon. Cool completely, about 2 hours, before slicing. Wrap tightly and store at room temperature up to 4 days, or refrigerate up to 10 days.