Line an 8x8-inch baking pan with aluminum foil or parchment paper. Set aside.
Microwave - To a medium microwave-safe bowl, add the sweetened condensed milk, white chocolate chips, and butter. Heat in the microwave in 30-second intervals, until chocolate is melted, about 3–4 min., stirring in between intervals.
Stovetop - Combine the white chocolate chips, sweetened condensed milk and butter in a medium saucepan and heat over medium while stirring continuously until the chocolate has melted completely.
Once mixture has melted, add ½ of the crushed up freeze-dried raspberries and fold to combine.
Pour the mixture into the prepared baking pan and spread it evenly. Add the remainder of the freeze-dried raspberries and swirl into the fudge.
Transfer it to the refrigerator for at least 3 hours or until completely set.
Remove the fudge from the pan. Slice into cubes by using a sharp knife warmed under hot water for clean slices. Serve and enjoy!