1. Preheat oven to 500°F. To make the crust, combine the bread crumbs, sugars, butter, and salt in a medium bowl until the bread crumbs are thoroughly coated. Press the mixture into the bottom of a 9-inch spring-form pan.
2. Cream the cheese, pumpkin, sugar, vanilla extract, spices, and lemon zest together. Beat in the eggs, one at a time, then the cream, and blend until smooth (if the batter is still lumpy, you can press it through a sieve). Pour the batter into the prepared pan, place in the oven, and immediately reduce the heat to 325°F.
3. Bake for 45 minutes to 1 hour, or until the filling is set. Cool thoroughly at room temperature before chilling.
TIP: This cake freezes well for up to 3 months