Make crust: Preheat oven to 400 degrees.
In a food processor blend together flour, sugar, salt and butter until mixture resembles meal. Add yolk and pulse until dough begins to come together but is still crumbly.
Press dough evenly onto bottom and up side of an 11-inch tart pan with a removable fluted rim. Prick bottom of crust all over with a fork and chill 30 minutes.
Bake crust in middle of oven 20 to 25 minutes, or until golden, and cool in pan on a rack.
Make filling: In a small bowl sprinkle gelatin over water to soften.
In a saucepan combine lemon juice, sugar, cinnamon, a pinch salt and 3 cups berries and simmer, stirring occasionally, 10 minutes. Remove pan from heat and stir in gelatin mixture and vanilla. Transfer blueberry mixture to a metal bowl set in a bowl of ice and cold water and stir until thickened to the consistency of raw egg white but not set, about 15 minutes. Fold in remaining 5 cups berries and pour filling into crust, spreading evenly. Chill tart, covered loosely, at least 4 hours, or until set, and up to 1 day.
Serve blueberry tar. t with whipped cream
courtesy Gourmet Magazine and author Leslie Pendleton