I haven’t quite mastered the ability to use cocoa to get an actual chocolate flavour, so we keep a tin of Carnation Hot Chocolate in the house. It’s quick and tasty, and easy to dress up.
You can make the mix with hot milk rather than water if you want a really creamy texture. The other option (that I use) is to toss a dollop of heavy cream (aka 36% whipping cream) into the mug.
I also add a dash of cinnamon for zing. If we’re spending an evening in, a little Irish cream will go a long way.
And voila! Special hot chocolate!