Step 1

Line the bottom of an 8 x 4 inch loaf pan with parchment paper.

Step 2

Add white chocolate chips and condensed milk to a large microwave safe mixing bowl. Heat chocolate in 15-30 second intervals, stirring in between with a spatula until chocolate is completely melted and the mixture is uniform. I like switching to a whisk to stire after the chocolate is mostly melted to ensure that you have a smooth, uniform mixture. You can also melt the chocolate and condensed milk on the stove using the double boiler method.

Step 3

Stir in the zest. Once the zest is added, you will notice the fudge start to thicken up right away. Working quickly, add the mixture into the prepared pan.

Step 4

Use a spatula to spread the fudge mixture evenly across the bottom of the pan and smooth the surface. Rap the bottom of the pan against your counter a few times to eliminate any air bubbles. If desired, sprinkle additional zest on the surface for decoration.

Step 5

Place fudge into freezer until set (about 30 minutes). The fudge is ready when it feels firm to the touch. Bring the fudge to room temperature before cutting with a sharp knife. Store uneaten fudge in the fridge or freezer.