Position a rack in the center of the oven and preheat the oven to 375° F.

In a medium bowl, stir together the vanilla wafer crumbs and granulated sugar. Mix in the melted butter until the crumbs are all moist and clump together slightly when you press them.

Transfer the mixture to a 9-inch springform pan and use the bottom of a glass or a measuring cup to press it evenly onto the bottom and about 2 inches up the sides of the pan.

Bake until the crust is fragrant and slightly darker, 9 to 12 minutes. Let the pan cool on a rack and lower the oven temperature to 300° F.

In a stand mixer fitted with the paddle attachment, beat the cream cheese, ricotta, flour, and a pinch of salt on medium speed, scraping down the sides of the bowl and paddle frequently, until very smooth and fluffy about 5 minutes.

Add the sugar and continue beating until fully blended and smooth.

Add the lemon zest and vanilla and beat until incorporated, about 30 seconds. Add the eggs one at a time, beating until just blended.

Pour the filling into the cooled crust and smooth the top. Bake at 300° F until the center jiggles when nudged, 55 to 65 minutes.

Set on a rack and cool completely, then cover and refrigerate until well chilled, at least 8 hours and up to 3 days.

When ready to serve, unclasp the springform pan and remove the side. Run a long, thin metal spatula under the bottom crust of the cheesecake. Carefully slide the cake onto a flat serving plate.

Spread lemon curd evenly over the top of the cheesecake. To cut, run a thin knife under hot water, wipe it dry, and cut the cake into slices, heating and wiping the knife after every slice.

Keep in the refrigerator, covered loosely with plastic wrap, for up to 5 days.