Preheat oven: 180°C / 160°C (fan) / Gas Mark 4 / 350°F
For the sponge, cream together the butter and sugar, either using a spatula, electric hand mixer or stand mixer, for several minutes until light and fluffy.
In a separate bowl, beat the eggs until whisked up to foamy, then add the eggs to the creamed butter and sugar and mix together until smooth.
Stir in the vanilla extract and then sieve in the flour, folding in gently till just combined.
Add in the milk and lightly mix until you only just have a smooth mixture.
Divide the mixture evenly between three lined cake tins and bake for 20-25mins, until the sponges no longer wobble, are springy to touch and a skewer comes out clean. Allow the sponges to cool on the side while you make the buttercream.
Beat the butter (either by hand, using an electric mixer or stand mixer) until pale, light and fluffy. This could take several minutes.
Sieve half of the icing sugar into the butter and beat until combined, then repeat this with the remaining half of icing sugar.
Once fully combined, add the orange extract, milk and orange colouring and beat until smooth.
Once the sponges have cooled completely, cut off any peaks to give smooth flat tops on your layers.
Spread a thick layer of buttercream on top of one sponge, then sandwich another sponge on top before repeating with the next layer. The top sponge layer should be upside-down to give a smooth top.
Smooth a thick layer of buttercream on top of the cake and around the sides, smoothing and scraping with your spatula and scraper until your cake has a relatively thin and neat outside crumb coating. Refrigerate for 15mins.
Add the remaining buttercream to the top and outside of the cake, smooth using a spatula and scraper.
Microwave your marshmallows for 15-20secs and then using your fingers of both hands pick up a pinch, spreading your fingers wide to create long strands of marshmallow. Wrap this around your cake and repeat until you have covered your cake on the top and sides.
For the spiders, pinch off a small amount of black fondant icing and roll it into a ball, lightly flatten it and then pinch off a smaller piece and roll it into a ball, brush a small amount of water onto one side and press it lightly on top of the body as the head.
For the legs, roll out 8 very small thin sausages and bend each at a right angle roughly ¾ of the way along. Brush a small amount of water to the tip of the short end and attach it to the spider body, pressing lightly.
Take another small pinch of icing, roll it into a small ball and flatten into an oval before brushing it with water and pressing it over the legs creating a top half og the body.
Repeat the above spider steps for the number you’d like to top your cake and press each one lightly into the sticky marshmallow webs.
Instead of plain flour, you can use self-raising flour and reduce the baking powder by 1tsp.