Bring milk to a boil in a medium saucepot over medium-high heat.
Lower the heat to medium then add the chocolate, whisking vigorously until the chocolate is completely melted.
Add the milk powder and cornstarch, still whisking, until everything is dissolved and the mixture is smooth and thick.
To serve, divide the hot chocolate among four mugs or glasses, then garnish each with a large dollop of whipped cream.
