1/2 cup unsalted butter
2 Tbsp sugar
2 egg yolks
1 cup all purpose flour
1 whisked egg white to seal the tart
8 ounces cream cheese, softened
1/4 cup sugar
1/4 cup creme fraîche or sour cream or yogurt
1/2 tsp vanilla extract
4 cups fresh blueberries
1/4 cup water
1/4 cup sugar
2 Tbsp cornstarch dissolved in 2 Tbsp water
To make the pastry beat the sugar and butter in a mixer until light and fluffy. Add the yolks, one at a time. Scrape down the bowl. Add the flour and mix until it is just combined. Wrap the pastry in plastic wrap and refrigerate it for one hour.
Roll out the dough and fit it into a 9″ round tart pan. Trim away the excess. Cover the tart shell and put it back in the refrigerator for about an hour.
Preheat the oven to 400 degrees F. Line the pastry shell with aluminum foil. Then fill the tart shell all the way up with pie weights or dry beans. Bake for 20 minutes. Very carefully remove the foil. Put the shell back in the oven for about 6 minutes, until lightly golden.
With a pastry brush, egg wash the crust with the whisked egg white. Let the shell cool completely.
To make the cream filling, cream the cream cheese and sugar in the mixer with the paddle attachment. Add the creme fraîche and vanilla and continue to beat until smooth. Fill the tart shell with the creme filling.
Put 3 cups of blueberries in a large bowl.
In a saucepan combine remaining of blueberries with 1/4 cup sugar and 1/4 cup water. Whisk together the 2 tablespoons of cornstarch and water in a measuring cup or bowl. Bring the berry mixture to a boil and them simmer until the sauce is thickened and really looking like jelly.
Pour the hot berry mixture over the waiting blueberries and mix gently so that all the fresh berries are covered. Then gently pour the berry mixture into the cream filled tart shell. Let the tart stand for about 30 minutes so that the berry mixture can firm up.
When you are ready to serve gently remove the tart from the pan.