Mint Extract: You can add more to taste, but many brands I’ve tried are very strong and if you use too much it can be overpowering, which is why I recommend starting out with just ⅛ teaspoon.
Stevia: As 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.
Topping/Garnish Ideas: A sprig of fresh mint, cacao nibs, shaved dark chocolate, or dark chocolate chips.