Step 1

Place the water in a small bowl. Sprinkle the gelatin over water and set aside to soften.

Step 2

If you plan to unmold the panna cotta onto plates, lightly coat the inside of 4 (6-ounce) ramekins or glasses with vegetable oil. Otherwise, you can leave them uncoated.

Step 3

Place the yogurt and 1/2 cup of the cream in a medium bowl and whisk to combine; set aside. Place the sugar and remaining 1/2 cup of cream in a small saucepan over low heat and bring to a simmer, stirring once or twice to dissolve the sugar, about 3 minutes.

Step 4

Remove from the heat and stir in the vanilla. Add the gelatin mixture and whisk to dissolve into the warm cream. Pour this mixture into the bowl of Greek yogurt and whisk until smooth.

Step 5

Divide the mixture evenly among the ramekins or glasses. Cover loosely with plastic wrap and refrigerate at least 4 hours or overnight.

Step 6

If serving with the macerated berries, place the raspberries, strawberries, and sugar in a small bowl and toss to combine. Let sit at room temperature for at least 30 minutes or up to 3 hours, stirring occasionally.

Step 7

Serve the panna cotta straight from the ramekins or, if you planned to unmold them, bring a small saucepan of water to a simmer and dip the bottom of one of the ramekins or glasses into the water for 5 seconds. Place a serving plate on top of the ramekin and invert it, shaking gently to help the panna cotta fall out. If it does not fall out easily, return to the warm water bath for another 2 seconds. Repeat with remaining ramekins.

Step 8

Top each panna cotta with the macerated berries or other topping (see suggestions below), and serve immediately.