Shortcrust pastry base: Take a large mixing bowl and combine ¾ cup all-purpose flour with 2 Tablespoons powdered sugar, ⅛ teaspoon salt, and 1 teaspoon lemon zest in it. Add ⅔ stick unsalted butter, cut into small pieces, followed by 1 egg yolk.
Start mixing with a fork, then use your hands to bring the dough together. Work quickly and do not over-knead—just mix until the dough comes together smoothly.
Shape the dough into a thick disc, wrap it in plastic wrap, and refrigerate for two hours to rest.
Meanwhile, prepare a springform cake pan with a removable bottom. Grease the base with a piece of solid fat. Cut a circle of baking paper to fit the bottom and press it into place—the fat will help it stay put.
Once the dough is chilled, put it onto the lined bottom and press it out evenly with your fingers. Prick the surface with a fork. Bake in a preheated oven at
340 °F for 17 minutes, until golden brown. Allow it to cool completely. Tvaroh filling: In a small bowl, whisk together ¾ cup granulated sugar and ⅓ cup cornstarch. Crack 3 eggs into a large mixing bowl. Beat them with an electric mixer fitted with a whisk attachment—start on low speed and gradually increase. Slowly add the sugar mixture while beating. Once fully added, increase the speed and continue whisking until the mixture becomes light and fluffy.
Add 1 Tablespoon lemon zest and ½ teaspoon vanilla extract and mix briefly.
Using an electric mixer with a whisk attachment, whip the cold ¾ cup heavy cream until it thickens. It does not have to be extra stiff—just firm.
Now switch to a hand spatula. Gently fold in 1 ⅔ pounds tvaroh cheese and whipped heavy cream in small batches, making sure each batch is fully incorporated before adding the next.
Grease the sides of the pan with butter, then pour in the tvaroh filling and smooth the surface.
Preheat the oven to
320 °F and bake for 35 minutes. Then lower the temperature to
270 °F and bake for an additional 20 minutes. Finally, turn off the oven, open the door slightly, and let the cake cool inside.