Firm enough to cut into neat squares, creamy enough to satisfy the most demanding cheesecake fans.
Ginger Crumb Crust
7ouncesgingersnaps or gingerwafers, broken into pieces
¼cup (½stick) unsalted butter, softened
Ginger Crumb Crust:Preheat the oven to 300°F. Butter an 8-inch square pan. Finely grind the cookies in a food processor (you should have about 1¾cups); add the soft butter and process until blended. Press the crumb mixture into the bottom of the baking pan and bake 6 minutes. Cool briefly while you make the filling.
Cheesecake Filling: Beat the cream cheese in an electric mixer until very smooth. Add the sugar and lemon zest and continue to beat until well blended. Add the eggs, one at a time; then the sour cream, lemon Juice, and vanilla, mixing until very smooth. Transfer the mixture to the baking pan, spreading it smooth with a spatula over the crumb crust.
Bake until set and the surface is gently but uniformly puffed, about 40 minutes. Cool the pan completely on a wire rack, then refrigerate until firm.
Glaze: Warm the marmalade until spreadable. Working gently, brush an even layer of marmalade over the chilled surface of the cheesecake. Chill again. Cut the cheesecake into 1-inch squares with a long thin knife dipped frequently in hot water. This cake will keep for a day or two, refrigerated. (If not serving all the squares at one time, cut only as many pieces as you need, placing a sheet of plastic wrap against the cut edges.)