I found a recipe for Peppermint Hot Cocoa Mix on the Frugal Family Fun Blog, I've changed it a little bit as I cannot find candy canes.
1 1/2 cups caster (powdered) sugar
1 cup + 2 Tbsp. cocoa powder (unsweetened)
To the caster sugar, add the cocoa powder
Stir, stir, stir! Make sure your mix is well-blended.
To make hot cocoa:
To 1 cup warm milk, add 1 1/2 - 2 Tbsp. mix.