Wash rice in several changes of cold water in a bowl until water is clear, then drain in a sieve. Combine with 1 cup plus 2 tablespoons water and 1/4 teaspoon salt in a medium saucepan. Bring to a boil, then reduce heat to low and cook, covered, until rice is tender and water is absorbed, 10 to 12 minutes. Remove from heat and let stand, covered, 5 minutes.

Spread rice on a large plate and let  5 minutes.

In a blender, combine rice, milk, ice, sugar and pinch salt. Purée to combine well. Divide among 4 serving glasses; dust with cocoa  stir before drinking.