When using the chocolate flavored stevia extract, follow the instructions on the label for 1 teaspoon equivalent measurement. It will usually say something like: 5 drops = 1 teaspoon, or 1/3 dropper = 1 teaspoon.
If you don't have the choc flavored stevia, just use normal stevia extract or another sweetener substitute of your choice.
This fudge will store in the fridge for a few weeks in an airtight container. Make a double or triple batch so you have a good supply on hand.