Preheat oven to 350 degrees F. On a floured surface, roll 1/2 Basic Pie Dough recipe to an 11-inch circle. Transfer dough to a 9-inch tart pan with a removable bottom. Press dough into corners; fold overhang into the pan and press firmly into the flutes. Freeze 15 minutes. Line tart pan with parchment paper, leaving an overhang, and fill with dried beans. Bake, on a rimmed baking sheet, until edges are golden brown, 30 to 35 minutes. Remove parchment and beans. Bake until bottom is light golden and dry, 5 to 10 minutes. Whisk together flour, buttermilk, granulated sugar, light brown sugar, eggs, lemon zest and juice, butter, and salt. Carefully pour into warm tart crust to within 1/4-inch of the top. Bake until filling is set, 50 to 60 minutes. Cool, on a rack, at least 2 hours. Remove tart ring and dust with confectioners' sugar.