2) Melt 30g of the butter in a frying pan over a medium-high heat. Add the pears and cook, stirring occasionally, until golden brown, about 7 mins. Stir in 1 tbsp of the brown sugar and 1 tsp of the pumpkin pie spice and remove the pan from the heat.
3) Sift the flour, ginger, the remaining 1 tsp of pumpkin pie spice, bicarbonate of soda, baking powder and salt in a large bowl.
4) In another bowl, whisk the milk, treacle, and remaining brown sugar. Add the eggs and whisk until smooth. Use a spatula to stir the treacle mixture into the dry ingredients to make a thick liquid batter.
5) Heat the water and remaining 30g butter in a small saucepan until just boiling. Whisk the hot water into to the batter until just combined. Stir in the pears. Pour the batter into the prepared tin.
6) Bake in the centre of the oven for about 40 minutes, until a toothpick inserted into the centre comes out clean.
7) Cool the cake in the tin on a rack. Cut into 12 squares. Dust with icing sugar before serving, if desired.
*Cook's Note: If you can't find pumpkin pie spice, you can make your own by stirring together 1 tsp cinnamon, 0.5 tsp ground ginger, 0.25 tsp ground cloves and 0.25 tsp grated nutmeg.