Pie Pastry

• 1½ cups (all-purpose) flour
• ½ teaspoon sugar
• ¾ cup lightly salted butter, frozen and cut into small bits
• 2 tablespoons solid vegetable shortening, frozen, and cut into small bits
• 2 tablespoons ice water
• 2 teaspoons fresh lemon juice

Lemon Filling

• 1 cup blanched whole almonds
• 3 tablespoons cornstarch
• ¼ cup milk
• 6 large eggs
• 9 large egg yolks
• 1 cup sugar
• 1¾ cups fresh lemon juice (about 7 lemons)
• ¼ cup grated lemon zest (about 6 lemons)
• ½ cup unsalted butter
• ¾ cup saltedbutter
• ½ teaspoon almond extract
• 1 tablespoon amaretto liqueur
• 1 large egg yolk
• 1 tablespoon heavy cream
• 1 tablespoon sugar

For the pie pastry, combine the flour and sugar in a mixing bowl or in the bowl of a food processor. Cut or process in the butter and shortening with on/off pulses until the mixture resembles coarse cornmeal. Mix the ice water and lemon juice and gradually work it into the flour mixture with your fingers. Or pour it through the feed tube of the processor with the motor running and process just until the dough barely holds together. Do not overwork the dough or it will be tough. It should look marbled or streaky where the butter is incompletely blended with the dry ingredients; when baked, these streaky areas will create the desired flakiness. Divide the dough in half and shape into 2 thick disks. Let rest a few minutes to allow the flour to absorb the liquid. Then wrap in a damp towel or plastic wrap and refrigerate at least 30 minutes.

For the filling, preheat the oven to 350°F. Spread the almonds in a single layer on a baking sheet and toast them until light gold in color, 7 to 10 minutes. Chop them medium fine and shake in a strainer to remove the almond dust, which would add an unpleasantly gritty texture to the filling.

Dissolve the cornstarch in the milk in a heavy medium saucepan. Add the eggs, egg yolks, sugar, lemon juice and zest, and butters. Bring to a boil over medium heat, stirring constantly, until the custard is thick and coats the back of a spoon, 7 to 10 minutes. Strain the filling into a bowl and stir in the chopped nuts, almond extract, and amaretto. Cool over ice water, stirring occasionally. Press a sheet of plastic wrap directly on the surface to prevent a skin from forming and refrigerate until ready to assemble the tart. (The filling can be refrigerated up to 2 days, but stir in the nuts just before assembling the tart.)

Preheat the oven to 350°F. Roll out each pastry disk into a 12-inch circle on a lightly floured surface. Refrigerate 1 circle on a baking sheet. Brush the flour from the second circle and ease into a 9- or 10-inch pie pan. Pour the filling into the pie shell and brush the edge with water. Lay the second pastry circle over the filling. Let stand a few minutes to let the dough soften, then fold the edges together and flute for a decorative edge. Cut a decorative vent in the top crust with a sharp knife to allow the steam to escape.

Lightly beat the egg yolk and cream together and brush over the pastry, then sprinkle with the sugar. Bake until the crust is golden brown, 45 to 60 minutes in a Pyrex pan or about 1 hour in a metal pan. Let cool completely and serve with whipped cream if you like.