Water buffalo yogurt is richer than the conventional kind.
FOR THE PANNA COTTA:
6 tbsp. sugar
1 vanilla bean, split in half lengthwise
1 1⁄2 cups plain buffalo milk yogurt, drained for 1 hour in a fine sieve
1 cup heavy cream
1 tsp. unflavored powdered gelatin
FOR THE RASPBERRY PURÉE:
4 cups fresh or thawed frozen raspberries
1 cup sugar
6 cups mixed fresh berries
1. For the panna cotta: Put sugar into a medium bowl, scrape insides from one-quarter of the vanilla bean into bowl (reserve rest of bean for another use), and, using your fingers, break up seeds and distribute throughout sugar. Add yogurt to sugar and whisk to combine.
2. Put 1⁄4 cup of the cream into a small pot and heat over medium heat until just hot. Remove from heat and stir in gelatin to dissolve it, 2-3 minutes. Add 1⁄2 cup of the yogurt mixture; whisk to combine. Whisk yogurt-gelatin mixture back into remaining yogurt mixture and set aside.
3. Put remaining cream into a large bowl and whisk to stiff peaks. Fold cream gently into yogurt mixture. (Use a whisk to gently finish combining ingredients, if necessary.) Divide mixture evenly between six 3"-wide ramekins (ramekins should be at least 1 1⁄2" tall). Transfer ramekins to a sheet pan, cover with plastic wrap, and refrigerate until completely set, 8 hours or overnight.
4. For the raspberry puree: Put raspberries, sugar, and 2 tbsp. water into a blender and puree. Press puree through a fine sieve, discarding solids.
5. To serve: Pour a little raspberry puree onto the middles of 6 plates. Set each ramekin in a hot-water bath for 1-2 minutes, run a sharp knife around the edges, and turn panna cotta out onto the plates. Place 1 cup of berries around each panna cotta and sprinkle plates with confectioners' sugar.