In a small bowl, sprinkle the gelatin on 3 tablespoons cold water. Stir and set aside for 10 minutes to allow the gelatin to dissolve.
Meanwhile, in a large bowl, whisk together 1 1/2 cups of the cream, the yogurt, vanilla extract, and vanilla seeds. Heat the remaining 1 1/2 cups of cream and the sugar in a small saucepan and bring to a simmer over medium heat just until the sugar dissolves. Off the heat, stir the softened gelatin into the hot cream and stir until dissolved. Pour the hot cream and gelatin mixture into the cream and yogurt mixture and stir in the Grand Marnier. Pour into 7 or 8 serving glasses and refrigerate uncovered until cold. When the panna cottas are thoroughly chilled, cover them with plastic wrap and refrigerate overnight.
Before serving, spoon 2 tablespoons of the Fresh Raspberry Sauce on each panna cotta and top with fresh raspberries. Serve cold.
Fresh Raspberry Sauce:
Place the raspberries, sugar, and 1/4 cup water in a small saucepan over medium heat. Bring to a boil, lower the heat, and simmer for 4 minutes. Pour the cooked raspberries, the jam, and the framboise into the bowl of a food processor fitted with the steel blade and process until smooth. Pour into a container and chill. The sauce can be refrigerated for up to one week.