Preheat the oven to 180°C/160°C fan/350°F/gas mark 4. Line a 2lb loaf tin (approx 11.5 x 21.5 cm / 4.5 x 8.5 in) with baking parchment.
Whisk together the pumpkin puree, treacle, golden syrup, brown sugar, oil, milk and vinegar in a large bowl until well combined.
240 g (1 cup) pumpkin puree, 100 g (5 Tablespoons) black treacle (or molasses), 100 g (5 tablespoons) golden syrup, 100 g (packed ½ cup) dark brown soft sugar, 82 g (6 Tablespoons) neutral oil (I use olive), 80 g (⅓ cup) unsweetened non-dairy milk (I use soy), 1 teaspoon vinegar
Whisk in the baking powder, bicarbonate of soda, ginger, cinnamon, nutmeg, allspice, cloves and salt.
1 teaspoon baking powder, ½ teaspoon bicarbonate of soda (baking soda), 3 teaspoons ground ginger, 1 teaspoon ground cinnamon, ¼ teaspoon ground nutmeg, ¼ teaspoon ground allspice, ⅛ teaspoon ground cloves, ¼ teaspoon salt
Finally add the flour, stir the batter with a balloon whisk until no dry lumps remain but be careful not to over-beat the mixture.
260 g (2 cups + 1 Tablespoon) plain (all-purpose) flour
Pour the batter into the prepared tin and bake for 1 hour until a skewer inserted into the centre comes out clean.
Leave to cool in the tin. Once cold, store in an airtight container.