Step 1

Preheat the oven to 180°C/350°F/Gas 4.

Step 2

Sift the flour and baking powder into a large bowl and add the sugar, margarine or butter and eggs.

Step 3

Beat until the mixture is smooth and creamy. Divide equally into 2 bowls and fold the orange rind and juice into one bowl and the blended cocoa powder into the other.

Step 4

Spoon each mixture into a greased and base-lined 18cm (7in) square tin and level the surface.

Step 5

Bake for 25-30 mins until the cakes are well risen and just firm to the touch. Cool for 5 mins, then turn out on to a cooling rack to cool completely.

Step 6

Trim the edges from each cake and cut each cake into 4 even-sized strips.

Step 7

Using some of the jam, sandwich two chocolate strips with 2 orange-flavoured strips to create the chequered effect.

Step 8

Roll out half the marzipan on a surface dusted lightly with icing sugar to an 18 x 30cm (7 x 12in) rectangle.

Step 9

Brush the top of the assembled cake with a little more jam and press on to the marzipan. Brush the remaining sides of the cake with jam and carefully wrap the marzipan all around the cake.

Step 10

Use your fingers to crimp along the top edges of the cake. Repeat with the remaining cake strips and marzipan to make a second cake.