Method

​1 For the cake: place the whole orange in a small saucepan, cover with boiling water and boil for 30 minutes, or until soft. Leave to cool.

​2 Preheat the oven to 180°C/fan 160°C/gas mark 4. Grease and line the bases of two 20cm (8inch) sandwich tins with greaseproof baking paper.

3 When the orange is cold, cut in quarters and remove any pips. Roughly chop the orange and blend the whole orange in a food processor. Set aside while you mix the cake ingredients.

4 Place the rest of the ingredients for the cake into the food processor and blend until smooth. Remove the blade from the mixer. Put to one side 2 tablespoons of the orange pulp (for the mascarpone icing) then carefully stir in the remainder of the orange pulp into the cake mixture.

5 Divide the cake mixture between the two prepared tins and level the tops. Bake for 30 minutes, or until well risen and lightly golden-brown. Leave to cool for a few minutes and then transfer to a wire rack to cool completely.

6 To make the orange curd: put your orange zest, juice, lemon juice, sugar and eggs in a glass bowl and whisk together. Sit the glass bowl over a pan of simmering water (without ever touching the water). Add the butter, cut into small cubes and stir continuously until the curd thickens (this may take about 10 minutes). Then remove the bowl and leave the curd to cool.

7 To make the mascarpone icing: put the butter into a mixing bowl and gradually beat in the icing sugar using an electric hand whisk. When the mixture is smooth add the mascarpone and beat together until thoroughly combined. Add the 2 tablespoons of orange pulp you've held back. Mix everything together until fully combined.

8 Once you’ve made both icings and the cake has cooled, it's time for assembly. Spread your orange curd between the two layers for the filling. Spread the orange mascarpone icing on the top. Now enjoy all that hard work!