Using an electric mixer, beat butter, sugars, pumpkin and vanilla in a large bowl until the mixture is pale and creamy (the pumpkin will breakdown and become smooth). Beat in eggs, one at a time, beating well between additions.
Stir in flour, bicarbonate of soda, mixed spice and ginger. Add the pecans, sultanas and salt. Use a wooden spoon to mix until well combined. Cover and refrigerate mixture for 1 hour or until firm enough to handle.
Meanwhile, preheat oven to 180C/160C fan-forced. Line 3 baking trays with non-stick baking paper.
Place rounded tablespoons of the mixture, about 5cm apart, on the lined trays. Bake for 12-15 minutes or until golden and puffed. Set aside on the trays for 5 minutes to cool before transferring to a wire rack to cool completely.
Store cookies between layers of baking paper in an airtight container for up to 1 week.