Place all ingredients in a food processor fitted with a metal blade and process just until mixture is powdery — about 30 seconds. Be careful not to overprocess. Store in an airtight container for up to 6 months. To make hot chocolate, combine 1 cup of milk and 2 tablespoons of this mix in a small saucepan and bring to a simmer over medium-low heat, stirring constantly until chocolate is incorporated and mixture is warmed through. Serve immediately.