Preheat the oven to 160° C Fan and line a 30x23cm deep square baking tin with baking paper, leaving some over the sides so that the cake can be taken out easily after baking.
Cream together the margarine and sugar until lighter and fluffy in texture.
400 g margarine, 380 g white sugar
Whisk in the eggs and vanilla extract one at a time until completely incorporated.
6 medium free-range eggs, 1 tsp vanilla extract
Add the flour, salt and Xanthan Gum to the wet ingredients and fold in until no pockets of flour remain.
400 g gluten-free self-raising flour, ¼ tsp Xanthan Gum, ¼ tsp salt
Transfer the mixture to the square baking tin and level off with an offset spatula.
Bake on the middle shelf for around 35 minutes or until an inserted toothpick comes out clean (See Notes).
Allow the cake the cool completely when done, before removing from the baking tin. Once cooled, cover evenly with the jam and sprinkle with desiccated coconut.
1 jar raspberry jam, 6-8 heaped tbsp desiccated coconunt
Serve warm with custard.
custard