Step 1
Preheat the oven to 220°C/fan oven 200°C/Gas Mark 7. Use a little TREX to grease a 23cm x 32cm Swiss roll tin. Line the base with baking paper and lightly grease with a little more TREX.

Step 2
Sift the flour and salt together and set aside.

Step 3
Using a hand-held electric mixer and a large mixing bowl, whisk the eggs and caster sugar together until very light in texture and pale in colour - this will take 3-4 minutes on full power. To check that the mixture is thick enough, switch off the mixer and lift up the beaters - they should leave a trail for a few seconds.

Step 4
Add the lemon zest and remaining melted TREX to the mixture and stir them in gently. Fold in the flour using a large metal spoon (not the electric whisk). Tip the mixture into the prepared tin and level the surface.

Step 5
Bake for 10-12 minutes until firm and springy to the touch. Turn the cake out onto a large piece of baking paper. Cover with a clean damp tea towel and cool completely. Remove the lining paper.

Step 6
Make the frosting by beating the TREX and icing sugar together until smooth and creamy. Add the lemon zest and elderflower cordial with a little food colouring.

Step 7
Use a 6cm cutter to stamp out 12 rounds from the cake. Sandwich together with a little frosting to make 6 cakes. Pipe or spread frosting over the tops and decorate with fresh berries and mint leaves.