Pulse the freeze-dried raspberries in a food processor until they form a fine powder.

Sift the raspberry powder through a fine sieve into a bowl to remove seeds. Set aside.

In a large heatproof bowl, combine the white chocolate chips and butter.

Heat the heavy cream in a small saucepan over low heat until it just begins to simmer. Do not boil.

Pour the hot cream over the white chocolate and butter. Let stand for 5 minutes.

Stir slowly until the mixture is smooth and fully melted.

Add ⅓ cup of the raspberry powder and mix until incorporated. Taste and add more raspberry powder as desired.

Cover the bowl with plastic wrap and refrigerate for 2 hours, or until firm enough to scoop.

Line a baking sheet with parchment paper. Scoop the mixture using a heaping teaspoon, roll into balls, and place on the sheet. Repeat to make about 24 truffles. Chill for 30 minutes.

Melt the bittersweet chocolate using a microwave (30-second intervals at 50% power, stirring between each) or over a double boiler.

Dip each truffle into the melted chocolate, tapping off excess. Return to the tray to set.

Optional: Sprinkle with remaining raspberry powder or chocolate sprinkles before the coating sets.