Pear, Nutmeg & Walnut Cake

Ingredients

• 3 brown pears quartered, cored, thinly sliced lengthways
• 2 tbsp rice vinegar or lemon juice
• 1 1/4 cups plain flour
• 1/2 cup walnut flour
• 2 tsp baking powder
• 1 packed cup soft brown sugar
• 150g/5oz butter melted, plus extra to grease
• 1 cup milk
• 1 tsp baking soda
• 1 egg
• 1 1/2 tsp freshly grated nutmeg
• 1 1/2 tsp ground ginger
• 3/4 cup walnut pieces
• 1 tbsp raw sugar to sprinkle