Turn the instant pot on via the slow cook button. Set time to 2 hours and 30 minutes. Chop the chocolate bar and place into the instant pot. Once it starts to melt stir fast and pour in the milk. It will clump up but don't worry as the instant pot heats up this will melt and leave specks of chocolate through out the hot cocoa. 

Mix together 2/3 cups cocoa powder with a few tablespoons of water. Mix it till it becomes a liquid paste. If you need more water then add a little more. You don't want it soupy, you want it to be a thick running paste like chocolate syrup. Check out the video below to visually see the consistency. Add this into the instant pot and stir well. 

Stir or whisk in the sugar. I suggest starting at 1 cup of sugar and tasting it. Just remember as the hot chocolate warms up the sugar will be sweeter. Add the sugar to your own taste buds. 

These are optional and not all people like cinnamon or nutmeg. Add them in and stir well. This is totally optional and if you do not add it to the hot chocolate it will still be super tasty.

Place the lid on the pot with the valve open. Stir every 30 minutes or so allowing the chocolate to mix in well. At about 2 hours the hot chocolate will be warm enough to serve. We add the extra 30 minutes depending on your instant pot and how long you want to keep it warm. 

Serve topped with whipped topping and cinnamon.