Line a rectangular pan and a baking sheet with wax paper and set aside.
Start by rolling 12 fondant spheres, about ¼" in diameter. You can use your cornstarch on your fingers to avoid the fondant from getting too sticky. Then, roll each sphere into a long strip, about 1 ½" in length.
Slightly fold over your strip and start twisting – this will act as your unicorn horn. Gently place each one on your lined baking sheet.
In two separate microwave-safe bowls, microwave each chocolate in 30 second intervals until they are completely melted. Stir in between each 30 second interval. Combine.
In a small saucepan, warm condensed milk over medium heat but do not allow to boil. Add condensed milk into melted chocolate and stir.
Pour into lined rectangular pan and tap to even it out. Pour sprinkles on top of the fudge, place the fondant horns and chill for approximately 3 hours before serving.