Preheat your oven to 160C fan. Prepare a rectangular baking tin - mine is approx 32cm x 21.5cm. I grease the tin and then use baking paper - the baking paper should go over the edges so you can lift out the cake once it's cooled.
In a large mixing bowl, cream together your caster sugar and your dairy free spread (or butter). Cream until lighter and fluffy. I use an electric hand whisk.
Gradually add your eggs and vanilla extract and whisk until combined
Fold in the desiccated coconut, gluten free self raising flour and xanthan gum to the mixture (this is a big mixture so make sure you carefully fold all the flour in properly)
Spoon/pour your mixture evenly into the baking tin. Place in the oven for about 60 minutes until fully cooked and golden.
Leave to cool in the tin and then lift out, using the baking paper and place on a cooling rack.
Once cooled spread your jam over the top of the sponge. (I always spoon my jam into a bowl first and mix it to smooth it out a bit as well as briefly putting in the microwave (30 seconds) - not to make it hot but to make it more spreadable)
Then sprinkle your desiccated coconut on top of the jam. As much or as little as you like.
Cut a thin strip off each side (but don't waste, they can be enjoyed!!). Then cut the sponge into squares.
Enjoy as they are or serve up with some custard (pink!) for a nostalgic school dinner treat!