Blueberry Cream Dessert

From Better Homes and Garden's Prizewinning Recipes cookbook.

Ingredients:
1 1/4 cups crushed graham crackers
1/4 cup sugar
1/3 cup butter, melted
1/2 cup sugar
1 envelope unflavored gelatin
3/4 cup cold water
1 cup sour cream
8-oz blueberry yogurt
1/2 tsp vanilla
1/2 cup whipping cream
1 cup fresh or frozen blueberries
fresh blueberries (optional)

Directions:
1. In a medium bowl, combine crushed graham crackers, 1/4 cup sugar, and melted butter. Reserve 1/4 cup of the crumb mixture; press remaining crumbs in bottom of a 2-quart square baking dish.
2. In a small saucepan stir together 1/2 cup sugar and the gelatin; stir in the water. Heat and stir until gelatin and sugar dissolve. In a large bowl combine sour cream and yogurt; gradually stir in gelatin mixture. Stir in vanilla. Chill about 45 minutes or until partially set (consistency of egg whites).
3. In a chilled small mixing bowl, beat whipping cream with chilled beaters of an electric mixer on medium speed until soft peaks form. Fold whipped cream into yogurt mixture. Stir in the 1 cup blueberries. Spoon into crust, spreading evenly. Chill about 4 hours or until set. Cut into squares. Sprinkle some of the reserved crumbs on top of each serving. If desired, garnish with additional blueberries.