Preheat the oven to 180 C / Gas mark 4. In a medium bowl, mix together the crushed gingernut biscuits, pecans and butter.
Press into the bottom, and about 2.5cm up the sides of a 23cm (9 in) springform tin. Bake base 10 minutes in the preheated oven. Set aside to cool.
In a medium bowl, mix together the cream cheese, 100g of the sugar and vanilla just until smooth. Mix in eggs one at a time, blending well after each.
Set aside 250ml of the mixture. Blend remaining sugar, pumpkin, cinnamon and nutmeg into the remaining mixture.
Spread the pumpkin mixture into the base, and drop the plain mixture by spoonfuls onto the top. Swirl with a knife to create a marbled effect.
Bake 55 minutes in the preheated oven, or until filling is set. Run a knife around the edge of the tin. Allow to cool before removing tin rim. Chill for at least 4 hours before serving.