Grate the zest from the orange and squeeze the juice (about 120ml/1 cup) into a large bowl. Snip the apricots into small pieces with scissors, then add the dried fruit and the marsala. Cover with cling film and leave to soak overnight.
The next day, rub a little of the butter around the inside of a 20cm round, deep cake tin, then line the base and sides with a double layer of parchment. Heat oven to 160C/140C fan/gas 3.
Put 200g of the biscuits in a large food bag, squish out the air, then bash the biscuits to fine crumbs. It doesn’t matter if there are a few nuggets left.
Put the remaining butter and the sugar into a large bowl and beat with an electric mixer for 2 mins or until paler and creamy.
Mix in the eggs, one by one. Sift in the flour, baking powder, mixed spice and 1 /4 tsp salt. Tip in the crumbs and beat together for a few seconds until evenly mixed.
Fold in the soaked fruit and almonds with a spatula.
Scrape the cake mixture into the prepared tin. Level the top and make a saucer-sized dimple in the middle of the batter. This will help your cake to rise evenly.
Bake for 2 hrs, then turn the oven down to 140C/fan 120C/ gas 1. Cover the cake with foil and bake for another 1 hr 30 mins or until risen and dark golden brown.
Check the cake is cooked by inserting a cocktail stick into the middle. It will come out dry when the cake is ready. Set on a cooling rack and leave for a few hours.
Using the cocktail stick, poke deep holes all over the cake. Slowly drizzle 2 tbsp marsala or sherry over the cake.
When completely cold, wrap the cake in clean baking parchment and store in a tin in a cool, dark place. Feed it every seven to 10 days until you are ready to decorate it.
Unwrap the cake and put it on a flat plate or board (25cm or bigger). Brush a thin layer of apricot glaze over the cake.
Sift a little of the royal icing sugar onto your work surface. Unwrap the marzipan and knead it with your hands until it feels softer.
Sprinkle the marzipan with more sugar and roll it to an even circle about 35cm across.
Lift the marzipan over the cake, smooth it down to the board, then trim with a knife. Don’t cut too close to the cake at first. You can smooth the icing with a jam jar or tumbler, then trim again if you need to
Spray the marzipan lightly with the gold spray. Spread the almonds out onto some baking parchment and spray these heavily.
Break four of the remaining 50g biscuits into nuggets using your fingers.
Mix the royal icing sugar with 4 tsp cold water. It should be thick but run very slowly when you drop it from the spoon. Spoon it over the cake and spread it to the edges, letting it drip here and there. Use a palette knife to help.
Put the whole biscuits on the cake first, then add the broken biscuits and the almonds in-between.
Put 1 tsp icing sugar in a fine sieve and shake a snowy dusting over the cake. Scatter the cake with the sugar balls, snowflakes or sprinkles, then leave the icing to set.