Put half the milk and half the golden syrup in a saucepan and bring to a gentle simmer. Stir until combined, then remove from the heat and set aside to cool. Or, heat the mixture in a heatproof jug in the microwave for 1 min. Meanwhile, oil two 20cm loose-bottomed cake tins, and line the bases with baking parchment (if the tins are less than 4cm deep, line the sides with a tall ring of baking parchment, too). Heat the oven to 180C/160C fan/gas 4.

For the sponges, you’ll need to use half the ingredients for the first batch of cakes, then the remaining ingredients for another batch, to make four sponges in total. For the first batch, tip 250g flour, 2 tsp baking powder, 250g sugar, 1 tsp cinnamon and 2 pinches of ground cloves into a large bowl with 1/4 tsp fine salt. Whisk together, breaking up any large lumps of sugar to create an even, sandy mixture.

Whisk together 150ml of the oil, 200ml buttermilk, 2 eggs and 1 tsp vanilla in a large jug. Add the cooled milk and syrup mixture, and whisk again. Gradually whisk the wet ingredients into the dry until smooth. Divide between the tins. Bake for 25-30 mins, or until a skewer inserted into the middle of each sponge comes out clean.

Leave the sponges to cool in the tins for 10 mins, then invert onto a wire rack (so the bases become the tops), peel off the parchment and leave to cool completely. Clean, oil and line the tins again as described in step 1, and repeat steps 1-3 to make two more sponges. Leave all four sponges to cool completely. Once cooled, the sponges can be wrapped and stored in a cool place for up to three days, or frozen for up to two months.

To make the buttercream icing, put the butter and half the icing sugar in a large bowl. Mash roughly with a spatula, then beat with an electric whisk until smooth and pale. Add the remaining sugar, the vanilla, and the milk to loosen the mixture to a spreadable consistency, if needed. Beat again until smooth. Transfer half the buttercream to a second bowl and set aside.

Working with the first bowl of of buttercream, spread a few tablespoons in the centre of a 20cm cake board or stand, and put one of the sponges on top, upside-down, so the flat base is on top. Spread over a quarter of the buttercream, followed by a third of the caramel. Top with another sponge, then another layer of buttercream and caramel, then repeat the process with a third sponge. Place the final sponge on top, upside-down, so you have a flat surface. Cover the entire cake in a very thin layer of the buttercream, using what remains from the first bowl – don’t worry about making it neat, as any crumbs trapped in the icing will be covered in the final coat. Chill the cake for 30 mins until the icing is firm.

Stand the chilled cake in a baking tray or large roasting tin (this will catch the sprinkles while you’re decorating). Using the second bowl of buttercream, spread some onto the cake to make a wide belt around the middle – this is easiest with a small offset spatula.

Press the sprinkles onto this band of icing using the palm of your hand until the entire belt is covered and the icing is no longer visible. Chill for 20 mins more until the icing and sprinkles are firm.

Using a small palette knife or offset spatula, dollop most of the remaining buttercream below and above the belt of sprinkles.

Then spread into thick bands that meet or slightly overlap the belt of sprinkles.

Use a cake scraper or the side of a large palette knife to smooth the bands of icing, turning the cake as you go, slightly edging over the sprinkles to create the impression of a fault line with sprinkles beneath. Don’t worry about the edges being too neat – a rough edge adds to the effect.

Cover the top of the cake with the remaining buttercream, using a small palette knife or cake scraper to smooth it. Use the gold decorating pen (or lustre and spirit mixture, plus a clean paint brush) to highlight the edges, including the inside edges, of the plain icing bands. If you like, you can also decorate the top of the cake with extra sprinkles. Best eaten within two days, but will keep in the fridge for up to five days. Leave to stand at room temperature for at least 1 hr before serving.