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1
Preheat oven to 350F.
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2
Pulse flour, sugar, salt, and butter in a food processor until mixture resembles coarse meal.
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3
Add yolk, vanilla, and lemon juice and pulse just until mixture begins to form a dough.
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4
Spread dough with a small offset spatula or back of a spoon over buttered bottom of a 24-centimeter springform pan and prick all over with a fork.
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5
Chill 30 minutes.
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6
Bake crust in a shallow baking pan (to catch drips) in middle of oven until golden brown, about 25 minutes, and cool on a rack.
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7
Increase temperature to 375F.
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8
Discard liquid and cheesecloth and force drained ricotta through sieve into bowl.
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9
Beat yolks and sugar with an electric mixer until thick and pale, then beat in ricotta, flour, and zests.
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10
Beat whites with salt in another bowl until they hold soft peaks, and fold into ricotta mixture.
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11
Butter side of springform pan and pour filling over crust (pan will be completely full).
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12
Bake in baking pan in middle of oven until cake is puffed and golden and a tester inserted 1 inch from center comes out clean, about 1 hour.
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13
Run a knife around top edge of cake to loosen and cool completely in springform pan on rack.
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14
Chill, loosely covered, at least 4 hours.
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15
Remove side of pan and transfer cake to a plate.
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16
Bring to room temperature before serving.
