COMBINE rice, barley, cinnamon sticks and cloves in a medium saucepan. Add 3 cups water to cover the mix. Bring mix to boil on medium high heat; reduce heat to low. Cover; cook for 20 minutes or until rice is soft (some additional water may need to be added to reach desired rice texture). Remove from heat. Let it stand for 15 minutes. Discard cinnamon sticks (cloves can stay). Stir in cinnamon, nutmeg and vanilla extract.
TRANSFER half of grain mixture to blender container. Pour in 1 1/2 cans of evaporated milk and 3/4 cup water. Cover; blend until smooth. Strain mixture through fine mesh strainer, into a wide mouth pitcher, using a spoon to press the grains against the strainer to get the most liquid out. Discard grains. Repeat with remaining grain mixture, evaporated milk and water. Stir in sugar to taste. Add additional water to thin to desired consistency, if necessary. Cover and refrigerate until well chilled, about 3 to 4 hours. Serve cold.