Combine the cream and sweetened condensed milk in a medium sauce pan and heat over low until the milk begins to steam.
Add in all of the chocolate and without stirring, let sit (off the heat) for 10 minutes.
Add the pan back to low heat and begin whisking the mixture until the chocolate is fully melted and combined.
Pour the mixture in the prepared pan and give it a few bangs on the counter to level it out.
Set aside to sit overnight. I covered mine with a paper towel to prevent anything from flying in it.
Once ready to cut, place chocolate on a clean surface. Heat your large knife up by running it under hot water and then quickly drying it off before cutting. Repeat the heating of the knife process every few cuts.
Cut the chocolate into ~1 inch pieces as evenly as possible. Optional: roll each piece in cocoa.
To make the Hot Chocolate on a Stick, place one marshmallow and one chocolate block on each stick.
When ready to drink, simple place the stick in a mug and pour steaming milk over top. Give it a good stir and wait a couple minutes for the chocolate to fully melt.