I also did a variation to the original recipe. Half the tartelettes had blueberries in the filing before being transferred into the oven to bake. The other half were baked with just plain filling. These were then topped with a fresh blueberry and apricot preserve compote. These tartalettes can be served either slightly warm or cold. We had them warm and they were absolutely delicious.
Lemon Blueberry Buttermilk Tart
(makes a 10" tart or seven 3 1/2" tartelettes)
For the Shell:
1 1/3 cup all-purpose flour
1/4 cup sugar
1/4 tsp salt
113g (1/2 cup) cold unsalted butter, cut into little bits
1 large egg yolk beaten with 2 TBsp ice water
Raw rice or beans (or baking weights) for weighting down the shell
For the Filling:
1 cup buttermilk **
3 large egg yolks
1/2 cup sugar
1 Tbsp freshly-grated lemon zest
1 Tbsp fresh lemon juice
56g (1/4 c) unsalted butter, melted and cooled
1 tsp vanilla
1/2 tsp salt
2 Tbsp all-purpose flour
2 cups blueberries
Icing sugar for sprinkling
** If you do not have buttermilk in your refrigerator, you don't need to run out purposely to buy a carton. Use the following method to make your own buttermilk.
1 cup of milk (less 1 Tbsp)
1 Tbsp white vinegar or lemon juice
Add both together and let stand for five minutes before using it.
Make the shell:
1) Stir together flour, sugar, and salt. Add the butter and blend until it resembles coarse meal. Add yolk mixture and toss until the liquid is incorporated. Form dough into a ball. Dust with flour and chill, wrapped in plastic wrap, for 1 hour.
2) Roll out dough to 1/8-inch thickness on a floured surface. Fit into a 10-inch tart pan with a removable fluted rim. Chill shell for at least 30 minutes or, covered, overnight.
(If you're making the tart all at once instead of chilling the crust overnight, this is a good point to melt the 1/2 stick of butter for the filling -- doing it now will give it time to cool off before adding it to the filling later)
3) Line shell with foil and fill the foil with rice. Bake shell in the middle of a preheated 180C (350C) oven for 25 minutes. Remove foil and rice carefully and bake the shell for 5 - 10 minutes more, or until pale golden. Let it cool in the pan on a rack.
Make the filling:
1) In a blender or food processor, blend the buttermilk, yolks, sugar, lemon zest and juice, butter, vanilla, salt and flour. Blend until smooth. Spread blueberries over the bottom of the tart shell and pour buttermilk mixture over top.
2) Bake tart in the middle of a preheated oven for 30 - 35 minutes or until filling is just set. (If you are making mini tarts, the baking time should be around 25 minutes or so)
3) Let tart cool completely in the pan on a rack. Then sprinkle with powdered sugar, sifted, and serve at room temperature or chilled, with ice cream if desired. Tarts can be refrigerated for up to 2 days - store in containers.