Chop the chocolate finely and set it aside. Line an 8-inch x 8-inch square baking pan with parchment paper.
Heat the sweetened condensed milk and orange extract (and orange zest, if you wish) in the microwave on 50% power for 30-45 second increments until it's hot.
Alternatively, in a medium saucepan over medium low heat, heat the sweetened condensed milk until it's very warm (not boiling). Remove it from the heat.
Add the chopped chocolate into the hot milk and stir gently with a silicone spatula until the chocolate is melted and the mixture is combined.
Pour the fudge mixture into the lined pan, smoothing out the top.
Chill the fudge in the refrigerator for about 2 hours, or until completely set.
Slice into small squares, garnish with some additional orange zest or orange slices (I like to dip my orange slices in sugar before garnishing) and serve.
Notes
Storage Instructions
Store this fudge in an airtight container for up to one week.
Freezer Instructions
This fudge freezes well and it can be stored in the freezer in an airtight container for up to 3 months.