Heat the oven to 200C/180C fan/gas 6. Oil a 900g loaf tin (ours was 19 x 9 x 6cm) and line with a long strip of baking parchment. Mix the flour, muscovado sugar, baking powder and ground ginger together in a large bowl. Tip in the oil, treacle, grated stem ginger and 170ml cold water, then beat together until smooth using a wooden spoon.

Pour the cake mixture into the prepared tin and bake in the centre of the oven for 45-50 mins until a skewer inserted into the middle comes out clean. Leave to cool in the tin for 5 mins, then transfer to a wire rack to cool fully.

Sieve the icing sugar into a bowl, add the ginger syrup and mix in just enough lemon juice to make a thick, pourable icing that can coat the back of a spoon. Put the cake on a plate or stand, remove the parchment and drizzle over the icing. Immediately scatter over the stem ginger. Cut the cake into thick slices to serve.