In a medium saucepan, combine 3 cups raspberries and 2/3 cup water. Simmer over low heat until raspberries are soft. Press mixture through a sieve or strainer to remove seeds and obtain raspberry pulp.
Place gelatin and 1/4 cup cold water in a small bowl. Set aside and allow gelatin to soften.
In a medium saucepan, whisk together raspberry pulp, egg yolks, and 2/3 cup sugar. Bring to a full boil, stirring constantly. Remove from heat.
Add gelatin to raspberry mixture and stir until dissolved. Place pan in a cold water bath to cool completely.
In a large glass or metal mixing bowl, beat egg whites until foamy. Add cream of tartar. Add 1/3 cup sugar a little at a time, beating constantly until whites are stiff and glossy.
In a separate mixing bowl, whip cream until stiff. Gently fold together with cooled raspberry mixture and meringue. Spoon mixture into graham cracker crust. Chill at least 2 hours before serving. Garnish with whole raspberries.