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