01 -
Line a 9 by 9 inch square pan with baking paper or parchment, leaving some hanging over the edges so you can lift the fudge out easily later. Set it aside.
02 -
Put the white chocolate, sweetened condensed milk, and butter in a large microwave-safe bowl. Microwave for 40 seconds at a time, stirring with a spatula after each interval, until everything is melted and smooth. This usually takes 2 to 3 cycles.
03 -
Stir in the bubblegum flavoring and vanilla extract until well combined. Add the white and pink food gel drops and swirl them through with your spatula to create a marbled pink and white effect. Don't overmix or you'll lose the pretty swirls.
04 -
Gently fold in the mini marshmallows and rainbow sprinkles, reserving a few sprinkles to scatter on top if you like.
05 -
Pour the fudge mixture into your prepared pan and spread it out evenly. Sprinkle the reserved rainbow sprinkles on top if using. Tap the pan gently on the counter a few times to remove any air bubbles.
06 -
Put the pan in the fridge and let it chill for at least 3 to 4 hours, or until the fudge is completely set and firm to the touch.
07 -
Lift the fudge out using the parchment paper overhang. Cut it into small squares with a sharp knife, wiping the knife clean between cuts for neat edges. Store in an airtight container.