Put 500 ml Oat milk into a pan and add 2 tablespoon Cocoa powder, 2 tablespoon Maple syrup and 1 teaspoon Vanilla extract.
Heat over a low heat, whisking continuously.
Add the 30 g Chocolate.
Continue heating until the chocolate has melted, about 2 minutes.
Notes
For a little kick of heat, you could add a pinch of cayenne pepper to the chocolate oat milk.
You can use another milk alternative like almond milk too, but it doesn't have the same kind of creaminess. You could use coconut milk instead, which would have the creaminess but it would totally change the flavour.
Don't let the oat milk boil. You will need to cook it on low.
If you are in a rush, you can cook this in the microwave.
To make this a really frothy hot chocolate, use a milk frother.
You can use a granulated sweetener instead of liquid sweetener if you prefer.