Preheat oven to 350°F. Spray bottom of 9×9×2" baking pan with nonstick cooking spray.

Finely grind gingersnaps in food processor. Add melted butter and 1 tablespoon lemon zest and process until crumbs are moistened. Press crumb mixture over bottom of prepared pan.Bake until crust is golden (~15 minutes). Cool crust completely on cooling rack.

Blend ricotta in clean food processor until smooth. Add cream cheese and sugar and blend well, stopping occasionally to scrape down sides of bowl. Blend in limoncello, vanilla and remaining lemon zest. Add eggs 1 at a time, and pulse until just blended. Scrape down sides of bowl as needed.

Pour cheese mixture over crust. Place baking pan in large roasting pan. Pour enough hot water into roasting pan to come halfway up sides of baking pan. Bake until cheesecake is golden and center moves slightly when pan is gently shaken (~1 hour). (Cake will become firm when cold.)

Transfer cake to rack; cool 1 hour. Refrigerate until cheesecake is cold (at least 8 hours and up to 2 days). Cut cake into squares and serve.