Place lemon juice in small bowl. Sprinkle gelatin over lemon juice. Let stand 5 minutes to soften gelatin.
Meanwhile, bring the cream, sugar, and lemon zest to simmer in heavy, medium saucepan over medium-high heat, stirring untill sugar dissolves. Remove from heat. Add gelatin mixture and whisk untill dissolved. Whisk in the buttermilk and vanilla until blended.
Ladle or pour mixture into 8 3/4 cup custard cups, ramekins, or small molds. Loosely cover with plastic wrap and chill 4 hours or up to overnight.
Cut around edge of each panna cotta to loosen. Set each cup in shallow bowl of hot water for 10 seconds. Immediately invert each onto a plate. Served with the crushed raspberry sauce. Makes 8 servings
CRUSHED RASPBERRY SAUCE
2 cups of fresh or frozen, thawed raspberries, undrained
3 tablespoons of sugar
Place raspberries and their juices in a medium bowl. Crush lightly with back of spoon. Stir in 3 tablespoons of sugar.