In a saucepan over low heat, warm the cream and sugar until sugar is dissolved. Remove from heat and add vanilla extract.
While cream is heating, pour the 6 tablespoons of water in a medium bowl. Sprinkle powdered gelatin over water and let sit for 5-10 minutes.
Pour warm cream mixture over gelatin mixture and whisk until gelatin is completely dissolved. Divide cream-gelatin mixture into prepared custard cups and chill for at least 2 hours, preferably 4 hours.
Once chilled, run a sharp knife around the edge of each panna cotta to loosen and carefully unmold onto a serving plate.
Raspberry Sauce
Combine all 4 ingredients in a small saucepan and let simmer over low heat for 10 minutes, until raspberries are cooked down. Strain raspberry sauce through a fine sieve to remove seeds. Pour strained sauce over panna cotta.