In a shallow nonreactive bowl, combine lemon slices and granulated sugar. Cover with plastic wrap; let macerate in refrigerator at least 4 hours or overnight.
Preheat oven to 350 degrees. In a medium bowl, lightly beat egg yolks and salt. Add lemon slices; gently toss to coat.
On a lightly floured surface, roll out one disk of cornmeal dough to a 12-inch round. Fit dough into a 10-inch fluted round tart pan with a removable bottom, pressing gently into corners and sides. Trim edges with a sharp paring knife.
Pour lemon filling into the tart shell, evenly distributing lemon slices. Dot with butter pieces. Roll out remaining dough disk. Carefully place it on the tart, pressing edges gently to adhere.
Whisk together egg and heavy cream in a small bowl; brush mixture evenly over top of dough. Sprinkle tart with pine nuts, and chill 30 minutes.
Place tart on a rimmed baking sheet, and bake until golden, about 40 minutes. Transfer to a wire rack to cool. Serve, sprinkled with confectioners' sugar.
If you don't have Meyer lemons, you can use regular, thin-skinned lemons: Before you begin, blanch the slices for one minute. Increase the amount of granulated sugar to one cup, and let lemon slices macerate overnight.