Crust
1 1/2 cups graham cracker crumbs
1/4 cup sugar
1/2 cup melted butter
Filling
1/2 cup sugar
1 envelope unflavored gelatin
3/4 cup cold water
1 cup sour cream
8 ounces blueberry yogurt
1/2 teaspoon vanilla extract
1/2 cup heavy whipping cream
1 cup fresh or frozen blueberries

Crust
Stir together all ingredients. Reserve 1/4 cup of mixture. Press remaining mixture onto bottom of 8 inch square baking dish.
Filling
In small saucepan stir together sugar, gelatin and water. Heat and stir till sugar and gelatin dissolve. Combine sour cream and yogurt and gradually stir in gelatin mixture. Stir in vanilla. Chill 45 minutes till partially set and of the consistency of unbeaten egg whites. Beat cream to soft peaks. Fold into yogurt mixture. Stir in blueberries. Spoon into crust and spread evenly. Chill 4 hours till set. Sprinkle reserved crumbs over top of each serving and garnish with additional blueberries if desired.