Start by adding your brown sugar, white sugar, cocoa powder and cornstarch to a sauce pan and whisk it together.
1/4 cup brown sugar, 1/4 cup white sugar, 1/4 cup cocoa powder, 2 tbsp cornstarch
Add in your egg yolks and 1/2 of your milk and mix until smooth. Turn the heat on to medium heat.
2 egg yolks, 2 cups milk
Once your mixture is smooth slowly whisk in the rest of your milk and stir over medium heat for 8-10 minutes or until the pudding is nice and thick.
Place in a bowl with clear plastic wrap pressed against the surface of the pudding to stop a skin from forming then place in the fridge for 4 hours - over night.