We all liked this pie, but agreed that it was a bit much for a slice of pie. This filling would be perfect as a tart filling-mini tarts. I could see these as a nice addition to a summer picnic, and they would be wonderful with or without the sour cream. That said, I'll post the filling recipe as the crust and flavoured whipped cream weren't really anything special.
From Maida Heatter's New Book of Great Desserts, 1982
6 cups fresh blueberries
1/4 cup cornflour (cornstarch)
1/4 cup cold water
3/4 cup boiling water
1 cup sugar (I used 3/4 cup and it was still sweet)
1/4 teaspoon salt
1 1/2 tablespoons fresh lemon juice
1 tablespoon unsalted butter
Set aside 1/2 cup of berries. In a small bowl, combine cornstarch in cold water until dissolved. Add boiling water and stir until smooth. Place in a 1 quart saucepan. Add sugar, salt, and reserved berries (the 1/2 cup). Cook over medium heat, stirring constantly. While you cook, smash the berries against the side of the pan with a wooden spoon. Cook until it comes to a boil, then thickens and becomes somewhat clear (about ten minutes). Reduce the heat to low, and cook 3-4 minutes longer.
Remove from heat, and stir in the lemon juice and butter. In a large bowl, combine it with the rest of the berries. Mix well. Chill at least three hours before using.