I am just pasting the recipe the way my dad sent it to me-I added several more shakes of salt though because I love salt and how it really brings out the flavor.
Jims Hot Cocoa:
2 parts water
1 part cocoa powder
1 part brown sugar (start with less - easy to add more later)
small dash of salt
Bring to low boil stirring constantly, add large dash of baking soda (e.g. 1/16 tsp for half cup cocoa), keep stirring until fizzing stops and bad smell dissipates (you're getting rid of the acid).
Remove from heat, add:
2 parts semi-sweet choc chips (e.g. regular Nestle)
1 part darker choc chips (or French Vanilla disks)
(You can vary that, e.g. use 1 part semi-sweet, 1 part milk chocolate chips).
Stir in until thoroughly blended, then return to medium heat and start adding milk by small amounts at first, blending in after each addition. Some cream is nice if you have some. Initially add milk slowly enough that the mixture stays warm & keeps the chocolate melted.
Keep adding milk until it tastes about right (usually I stop right after I've added just a little too much). Add vanilla. Add sugar if needed (especially if you started with half the expected amount).
If too sweet, adding milk can reduces sweetness some.
All of this is very approximate.