Melt the chocolate in a microwave or double boiler.
Heat 3 cups of milk in a medium saucepan over medium heat until steaming and starting to bubble around the outside.
Whisk the melted chocolate, espresso powder, vanilla, peppermint, sea salt, and stevia/erythritol packets into the milk in the saucepan and heat until bubbling around the outside, whisking occasionally.
Add the remaining ½ cup milk to a pint-sized glass jar; put the lid on and shake vigorously until doubled in volume, about 30 to 60 seconds. Uncover the jar and microwave until warm, but not hot, about 30 seconds.
Pour the mocha into 4 mugs; top each with milk foam and serve.
Notes
Stevia or Other Sweetener: Instead of stevia, you can use any sweetener you like in this recipe, such as maple syrup, honey, etc. Here is a guideline on how sweet 1 packet of stevia is: the amount of stevia in 1 packet measures ½ teaspoon, which is about as sweet as 2 to 3 teaspoons of regular sugar.
I use Medaglia D’Oro espresso powder, and for the biggest savings I like to buy it in bulk on Amazon. It’s also available in a 2 oz jar if you just want to try it out. Just a little bit of it adds another delicious level of flavor and complexity to baked goods and quick drinks!