Preheat the oven to 180°C and line a 20cm round cake tin with parchment.
Sprinkle the demerara sugar on the base and arrange the pear halves cut-side down with a cherry in each center.
Melt the butter, golden syrup, and treacle in a small pan over low heat.
Whisk the egg, 150ml milk, and bicarbonate of soda together in a jug.
Sift the flour and spices into a bowl and stir in the brown sugar.
Mix the melted fats and egg mixture into the dry ingredients until combined.
Pour the batter over the pears and bake for 45 minutes.
Cool for 4 minutes before turning out onto a plate to serve warm.