Accompaniment: vanilla ice cream Special equipment: parchment paper Preheat oven to 400°F. Line bottom of a buttered 8- by 2-inch round cake pan with 2 rounds of parchment paper, then butter parchment. Dust pan with some flour, knocking out excess. Arrange blackberries in 1 layer in cake pan. Sprinkle berries with 11/2 tablespoons sugar and shake pan to help distribute sugar. Whisk together 1 cup flour, baking soda, and salt in a bowl. Beat together butter and remaining 1/2 cup sugar in a large bowl with an electric mixer at high speed until light and fluffy, about 2 minutes. Add egg and vanilla and mix at low speed until just incorporated. Alternately add flour mixture and buttermilk in 3 batches, mixing at low speed until just incorporated. Spoon batter evenly over berries, smoothing top, and bake in middle of oven until top is golden and a tester comes out clean, 30 to 35 minutes. Run a thin knife around edge of pan, then invert a large plate over pan and, using pot holders to hold plate and pan together tightly, flip cake onto plate. Peel off parchment and serve cake with ice cream. Makes 6 servings. Gourmet September 2002