Chocolate Pudding For Grownups

Add half & half, both sugars and salt into a medium (2 qt) saucepan over medium low heat. Cook until you see steam coming off the top of the liquid.
While half & half mixture is heating, combine cornstarch and milk in a bowl and blend until smooth. You want this slurry to be as lump-free as possible. Have a fine-mesh strainer handy, you'll use it in the next step.
once half & half starts to steam, add the cornstarch slurry through the strainer, catching any errant lumps. Add the espresso to the saucepan. Cook, stirring occasionally with a whisk, until it barely reaches a boil (this will take around 5 mn.) The mixture will thicken.
Reduce heat to very low, stirring and cooking for another 5 mn or so, until fairly thick. The consistency should be thick enough to thickly coat a spoon.
Remove saucepan from heat, add in the chocolate and let it sit in the mixture, slowly melting on its own for 1 mn. After that, add softened butter and stir to fully incorporate everything. Pour the pudding into 4 (4 oz) ramekins or little bowls. If you are anti-pudding skin, lay plastic wrap on the surface of the pudding to prevent skin from forming. The plastic wrap can be buttered so you don't lose any precious pudding during wrap removal.
Refrigerate until chilled. Remove ramekins from fridge 10-15 mn before serving.