Vegetable-oil cooking spray
1 stick (8 tablespoons) cold unsalted
butter, cut into small pieces
1/4 cup sugar
1 cup all-purpose flour, plus more
for dusting
1 teaspoon freshly ground pepper
1/8 teaspoon salt
FOR THE FILLING
8 large egg yolks
2 tablespoons finely grated lemon
zest
1 cup fresh lemon juice
2 cans (each 14 ounces) sweetened
condensed milk
1/8 teaspoon salt
Make the crust: Preheat oven to 325
degrees. Coat six 4-inch and ten 3-inch round fluted tart pans with cooking
spray. Place 4-inch pans on one rimmed baking sheet and 3-inch pans on another
baking sheet.
With a mixer on medium-low speed,
beat butter and sugar until just combined, about 30 seconds. Add flour, pepper,
and salt, and beat 1 minute. Raise speed to medium-high, and beat until a dough
forms, about 4 minutes.
On a lightly floured work surface,
roll out dough to 1/4 inch thick. Cut out 31/4-inch circles and place in the
4-inch tart tins, pressing slightly to fill just the bottoms. Cut out 21/4-inch
circles and place in 3-inch tart tins, pressing slightly to fill just the
bottoms. Bake until pale golden brown, about 20 minutes. Let cool on sheets.
(Leave oven on.)
Make the filling: Whisk egg yolks,
lemon zest, lemon juice, condensed milk, and salt until smooth. Pour into tart
pans. Bake until edges of filling are firm and slightly puffed, about 10
minutes for 3-inch tarts and 14 minutes for 4-inch tarts. Let cool. Refrigerate
for 1 hour, then remove sides of tart pans (leaving the base), and refrigerate,
uncovered, at least 4 hours, preferably overnight.