Pistachio Blackberry Tea Fingers

Preheat oven to 350 F.

Grind pistachios finely and measure 1/3 cup.

Sift together pastry flour, sugar, baking powder and salt. Add oil, egg yolks, lemon juice, water and vanilla and beat mixture in a mixer or with electric beaters until thick, about 4 minutes.

Whip egg whites with cream of tartar to stiff peaks. Fold one-third of whites into batter, then remaining two-thirds. Pour batter into ungreased 10-inch springform pan (or an ungreased bundt pan) and bake for 45-55 minutes, until springy when touched.

Allow to cool completely before removing from pan.

Slice pistachio sponge horizontally twice and trim edges to make squares.

Spread squares with a thin layer of mascarpone cheese and cut into rectangles,
1 x 2 inches.

Place 2 blackberries on each half of the rectangles and top with another segment of sponge, mascarpone side down. Dust tops with icing sugar to serve.