Preheat the oven to 180°C/gas mark 4

Butter and line the base and sides of a 20cm round deep cake tin with baking paper

Place the butter, sugar and orange zest in a mixer and beat until light and fluffy (you can also do this by hand). Add the beaten egg, a little at a time, mixing well in between each addition. Fold in the flour, semolina and buttermilk and spoon into the prepared cake tin

Level the mixture and arrange the rhubarb in a circular pattern, filling any space in the middle with smaller pieces. Sprinkle all over with Demerara sugar

Place the tin in the pre-heated oven and bake for 45 minutes – 1 hour (or until a skewer inserted into the middle comes out clean of mixture)

Meanwhile, make the drizzle syrup by putting the chopped rhubarb, caster sugar, orange juice and water in a small pan over a low heat. Stir until the sugar dissolves then increase the heat and bring to the boil. Reduce the heat again and simmer for 10–12 minutes until the syrup has thickened. Strain through a sieve into a small bowl and set aside

When the cake is ready, remove it from the oven and leave for 5 minutes before turning it out on a wire rack top side up. Drizzle over a few tablespoons of the syrup and allow to cool. Dust with icing sugar

The cake can be served warm with a little more syrup and cream, or cold, but it is best eaten on the day it is made