Blueberry Buttermilk Tart
From Geoff Last
Buttermilk has become one of my favourite ingredients for baking; I often substitute it for regular milk in everything from pancakes to Yorkshire pudding. It adds a zesty tang that just lifts things up a notch. This tart is obviously best when blueberries are in season but I enjoy it in the winter as well, perhaps because it reminds me of summer. Frozen blueberries work just fine, thaw them first and drain off the collected juices so they don’t make the crust soggy.
1-1/3 c. unbleached white flour
1/4 c. sugar
1/4 t. cinnamon
1/4 t. salt
1/2 c. cold, unsalted butter, cut into 1/2-inch chunks
1 egg yolk, beaten with 3 T. ice water
pie weights (rice, dried beans or any other pie weights)
1 c. buttermilk
3 large egg yolks
1/2 c sugar
1 T. grated lemon zest
1 T. lemon juice
1/4 c. unsalted butter (1/2 stick), melted and cooled
1 t. vanilla extract
1/2 t. salt
2 T. unbleached white flour
2 c. blueberries, fresh or frozen, defrosted and drained
1 T. icing sugar for dusting
Make the shell: in a bowl stir together the flour, sugar, cinnamon and salt, then add the butter and blend the mixture until it resembles coarse meal (use a food processor, two knifes or a pastry blender). Add the yolk mixture and toss with the flour mixture until the liquid is incorporated. Form the dough into a ball. Dust the dough with flour and chill it, wrapped in plastic wrap, for 1 hour. Roll out the dough 1/8-inch thick on a floured surface, fit it into a 10-inch tart pan with a removable fluted rim, and chill the shell for at least 30 minutes or, covered, overnight. Line the shell with foil, fill the foil with the pie weights and bake the shell in the middle of a preheated 350°F oven for 25 minutes. Remove the foil and pie weights carefully, bake the shell for 5 to 10 minutes more, or until it is pale golden, and let it cool in the pan on a rack.
Make the filling: in a blender or food processor, blend together the buttermilk, yolks, granulated sugar, zest, lemon juice, butter, vanilla, salt and flour until the mixture is smooth. Spread the blueberries evenly over the bottom of the shell and pour the buttermilk mixture over them. Bake the tart in the middle of a preheated 350°F oven for 30 to 35 minutes, or until the filling is just set.
Let the tart cool completely in the pan on a rack, sprinkle it with sifted icing sugar, and serve it at room temperature or chilled with vanilla ice cream or gelato.