Place milk in 2-cup glass measuring cup. Microwave on 100 percent power (high) until hot, about 2 minutes 20 seconds. Place hot milk and sugar in a blender container. Cover with a vented lid and blend until frothy, about 1 minute. To serve, divide coffee among 4 cups. Top each with frothy milk. Sprinkle with cinnamon or grated chocolate. Makes 4 servings.