You'll need two 6-oz. ramekins for this recipe. Fill the ramekins with water and set aside.
Pour 1.5 tablespoons of water in a cup and add the gelatin powder. Mix and let sit until the water has been absorbed by the gelatin.
Transfer blackberries, orange juice and sugar into a saucepan and cook on low heat for about 3 minutes until sugar dissolves and berries are soft. (NOTE 1)
Pour into a food processor or use a immersion blender and process until smooth.
Strain mixture through a sieve; blackberries have tiny hard particles that should not be in your dessert.
Taste and add more sugar if needed. Add the gelatin and mix until well blended.
Allow to cool just a little and mix in the yogurt. Stir until well blended. Empty the ramekins and divide the panna cotta over the ramekins. (NOTE 2)
Cover and refrigerate for at least 4 hours to set.
To serve, you can run a knife between the panna cotta and the ramekins or dip the ramekin in hot water. Flip around and serve on plate or shallow bowl. (NOTE 3)
Notes
Use water or lemon juice instead of orange juice.
Use full cream of low fat yogurt.
Use a small knife and insert it between the panna cotta and the ramekin, just enough to get some air between the two. Then hold the ramekin in your hand, with the panna cotta facing you. Lightly press the panna cotta with your dry fingers, so that the tiny 'opening' you made with the knife comes loose from the ramekin. Now turn the ramekin in your hand and and keep working your fingers to loosen the dessert from the ramekin, all the way around the ramekin. Place a small plate or a shallow bowl on top of the ramekin and flip it over. Give it a quick firm but controlled shake and the panna cotta will come loose from the bottom as well.