Creamy Lemon-and-raspberry Tart

To make the Sweet-Tart Dough: Using an electric mixer fitted with the
paddle attachment, beat the butter until soft and very smooth. Add the
confectioners’ sugar, and beat until blended. Add the flour and salt.
With the mixer running at low speed, beat the dough until it becomes
crumbly. Add the egg, and continue mixing until the dough just comes
together (do not overwork it). Turn out the dough onto a work
surface, and gather into a ball. Cut in half, and shape each half
into a disk. Wrap both pieces of the dough in plastic. Refrigerate at
least 1 hour. Lightly butter the insides of two 8- by 3/4-inch round
tart rings. Place the rings on a baking sheet lined with parchment
paper. Working on a lightly floured work surface, roll one disk of
the dough to an 1/8-inch thickness. Fit the dough into a tart ring,
pressing lightly against the bottom and up the sides. Run your
rolling pin against the rim of the circle, and cut off the excess.
Repeat with second disk of dough and tart ring. Chill 30 minutes.
Heat oven to 350 degrees with rack in center. Line each tart shell
with a circle of parchment paper, and fill shells with pie weights or
dried beans. Bake crusts 15 minutes, remove the paper and beans, and
bake just until the edges of the crusts are golden, 3 to 5 minutes.
Transfer baking sheet to a rack to cool. To make the Filling: Grate
the zest of each lemon using the small holes of a box grater, and set
aside. With a small knife, cut off enough of the top and bottom of
each lemon, exposing the flesh. Stand the lemons on end, and
carefully cut away the white pith and a tiny bit of the flesh from
the entire surface of each lemon; the juicy sections of lemon should
now be completely exposed. Lay the lemons on their sides, and cut
each lemon crosswise into 1/2-inch-thick slices; remove seeds. Place
lemon slices, whole eggs, egg yolk, granulated sugar, and heavy cream
in the jar of a blender, and puree until smooth. Strain the mixture
into a bowl, and whisk in the reserved lemon zest. Lower the oven
temperature to 300 degrees. Scatter the raspberries over the bottom
of the two crusts. Pour the lemon filling into crusts. Bake tarts
just until the filling has set in the centers, about 25 minutes; the
filling should not shimmy when the edges of the tarts are tapped
lightly. Transfer tarts to a wire rack to cool. Serve. Makes 2 tarts.