Prepare Essential EatingWell Pie Pastry; refrigerate as directed.
Position rack in upper third of oven; preheat to 375 °F. Coat a 10- or 11-inch removable-bottom tart pan with cooking spray.
Roll out the dough on a lightly floured surface into a 12-inch circle. Drape the dough over the rolling pin and transfer it to the prepared pan. Press to fit. Run the rolling pin over the top of the tart pan to trim the edges. Cover the crust with foil or parchment paper and weight with pie weights, dry beans or dry rice. Place the tart pan on a baking sheet.
Bake the crust until the surface is set but not at all browned, 10 to 12 minutes. Remove the foil and pie weights.
Whisk eggs, egg whites and sugar in a mixing bowl until smooth. Whisk in lemon zest and lemon juice. Pour the filling into the partially baked crust.
Bake the tart on the baking sheet in the upper third of the oven until the crust is golden and the filling is set, about 20 minutes. Cool on a wire rack for at least 10 minutes. Dust with confectioners' sugar. Serve warm or at room temperature.
Equipment: 10- or 11-inch removable-bottom tart pan