Put the chia seeds in a bowl. Add 150ml (5 fl oz) of water. Stir, then pop in the fridge for 10 minutes.
Prepare your Christmas cake tin
Prepare your baking tin by greasing and then triple lining with two layers of baking paper on the inside and one layer of brown paper on the outside. For step-by-step images showing how to do this, follow my foolproof guide to lining a Christmas cake tin here.
Make your Christmas cake
Preheat the oven to 140C (120C fan).
Put the plant butter and sugar in a large bowl. Cream together until slightly pale and fluffy.
Stir in the chia seed mixture and treacle.
Add the flour, ground almonds, mixed spice, nutmeg, orange zest and lemon zest. Fold through.
Stir in the lemon juice, orange juice and soya milk.
Add the mixed fruit, mixed peel, glacé cherries and flaked almonds. Mix and make a wish!
Spoon your cake mix into your prepared tin and level off.
Cover the top with a piece of baking paper with a small hole in the centre. This protects the top of the cake from burning during the long, slow cook in the oven.
Bake your Christmas cake in the oven for 3 to 3 1/2 hours. It’s ready when a skewer pushed into the centre of the cake comes out clean. Once baked, allow the cake to cool in its tin for 15 minutes, then transfer the cake to a wire rack to cool completely.
Cover your Christmas cake
When your cake has cooled, turn upside down so that the flat edge is on top and plce on a serving board.
If there are any holes or dips, fill them with a little bit of marzipan.
Brush all over with a thin layer of apricot jam. This will help the marzipan stick.
Dust your work surface with icing sugar and roll your marzipan out. Use the bottom of your cake tin as a guide to cut our a disc shape the same size as your cake. Gently lay the marzipan on top of the cake.
Dust your work surface with icing sugar again. Roll your white sugar paste out so that it is, large enough to cover the whole cake and down the sides with a little to spare.
Roll the sugar paste over your rolling pin, then gently lay on top of the cake, smooth off down the sides with the palm of your hand. Trim the base with a sharp knife.
Decorate your cake
You can now use your white fondant offcuts, plus you selection of coloured fondant icing to create a 2D or 3D Christmas scene.
I made three baubles, a sprig of holly and a little gingerbread man, fixed in place with a dab of cold water on a paint brush.