01 - Place chopped white chocolate in a large heatproof bowl.
02 - In a small saucepan, heat heavy cream and butter over medium heat until just simmering. Carefully pour the hot mixture over the white chocolate. Let stand for 2 minutes before stirring.
03 - Stir the mixture until smooth and glossy. Add vanilla extract and a pinch of salt, mixing until fully blended.
04 - Separate the chocolate mixture evenly into three bowls. Tint one bowl with red gel food coloring and fold in crushed freeze-dried raspberries. Tint another with blue gel food coloring and fold in crushed freeze-dried blueberries. Leave the third portion plain for the white color.
05 - Refrigerate all three bowls for 45 minutes, or until the mixtures are firm enough to shape.
06 - Using a small scoop or teaspoon, take about 1/2 teaspoon from each bowl. Press together and gently roll between your palms to form a tricolor ball. Repeat with remaining mixture.
07 - Roll each finished ball in white nonpareil sprinkles or sanding sugar to coat for a festive finish.
08 - Place the finished truffles on a parchment-lined baking sheet. Refrigerate for 20 minutes to set before serving.