Measure out your dry hot chocolate mixture. If using corn starch or potato starch for a thicker hot chocolate, add it to the dry hot chocolate mixture along with extra sugar (if using) and stir well to combine. Spices such as cinnamon or cayenne can also be added here. If using cayenne, a generous pinch is enough.
Warm up milk in a large* saucepan until it's gently boiling. If saucepan is too small it may boil over when the dry mixture is added.
Add the mixture to the saucepan and whisk for 2 minutes until dissolved. If you added the starch, it will also have thickened.
Optional: If you are adding gelatin, pour in to the jug of a blender and add the gelatin while the blender is running (if your blender has a top opening). This prevents clumping.
Pour in to a mug and enjoy!