01 - Place the finely chopped white chocolate in a heatproof mixing bowl.
02 - In a small saucepan, gently heat heavy cream and unsalted butter over medium heat until simmering. Immediately pour over the white chocolate and allow to stand for 2 minutes.
03 - Stir the mixture with a rubber spatula until smooth and glossy.
04 - Add the vanilla extract and a pinch of salt to the melted chocolate, mixing until fully integrated.
05 - Separate the mixture evenly into three bowls. Tint one portion with red gel food coloring and fold in the crushed freeze-dried raspberries. Tint another with blue gel food coloring and fold in the crushed freeze-dried blueberries. Leave the remaining third plain.
06 - Refrigerate all three bowls for 45 minutes or until the chocolate is firm enough to scoop.
07 - Using a truffle scoop or teaspoon, take approximately 1/2 teaspoon from each color. Press together and gently roll between your palms to create a tricolor sphere. Continue until all mixture is used.
08 - Roll each finished truffle in white nonpareil sprinkles or sanding sugar to coat.
09 - Set the truffles on a baking sheet lined with parchment paper and refrigerate for 20 minutes until firm. Serve chilled.