Add the white chocolate chips and the sweetened condensed milk to a microwave-safe bowl. Microwave for 30 seconds. Using a rubber scraper stir the mixture. Return to the microwave and cook for another 30 seconds. Stir in the vanilla extract.
Once you've added the sprinkles, chill the fudge in the refrigerator for 6-8 hours. This will allow the fudge to become firm and able to cut easily and in uniform squares.