Pre-heat your oven to 160C Fan/180C/350F/Gas Mark 4, and grease and line a 12" x 9" traybake tin
Make the cake by mixing the baking spread (or butter) and light brown soft sugar in a large bowl until fluffy, about 2-3 minutes, ideally using an electric mixer
Add the eggs, milk and vanilla extract, and mix until fully incorporated
Gently mix or fold in the self raising flour, cocoa powder, baking powder and bicarbonate of soda
Pour the mixture into the tin, smooth it out if needed to spread it out evenly
Bake for 25-30 minutes or until a skewer inserted in the centre comes out clean. Leave to cool fully either in the tin or on a cooling rack
While the cake is baking and cooling, make the biscuit graves. Snap about a third of the biscuit off at the end, this makes them a bit shorter and a better size for the cake. Melt the dark chocolate and dip the biscuit into it, shaking off any excess gently, place onto baking paper to set. Once the dark chocolate is set, melt the white candy melts and put in a piping bag. Snip a small bit off the end of the piping bag. Pipe on your chosen designs, then leave to set
To make the chocolate buttercream, mix the butter in an electric mixer with the paddle attachment for a few minutes. Add the icing sugar, cocoa powder and milk and mix until well combined. You can add more milk if the buttercream is too stiff
Ideally using an angled palette knife, spread the buttercream all over the top and sides of the cake
Break the chocolate fingers into varying lengths, stick them around the sides of the cake with the broken side down, push them gently into the buttercream so they stick to the cake. Then cover the top of the cake with the Oreo crumbs
Use a knife to cut slits in the top of the cake where you want the biscuit graves to go, then gently push them into the slits. Decorate the rest of the cake with the jelly snakes, fondant pumpkins, or whatever decor you have
Make the green grass buttercream by mixing together the butter and icing sugar, then add the vanilla and green food colouring, and mix until smooth and the desired shade is achieved. For best results use a stand mixer with the paddle attachment or a handheld electric mixer
Put the green buttercream into a piping bag fitted with a multi opening grass nozzle, and add some "grass" around the biscuit graves, and in random places all over the cake. Or add small blobs with a spoon and use the back of a spoon to flick the buttercream around and create texture
To serve, slice into squares. Store any leftovers in an airtight container in a cool place and eat within 3 days
Video
Notes
Make sure all your ingredients (particularly the butter and eggs) are at room temperature before you start baking.
I used a baking spread for the cake and unsalted butter for the buttercream.
If you can't get hold of light brown soft sugar, you can also use regular caster sugar for this cake.
You will need a 12" x 9" traybake tin for this recipe. However, if you want to make it in a 9" square tin, check the recipe notes for the measurement details.
I used Cadbury chocolate fingers around the cake, you could also use kit kats or chocolate matchmakers, or any long chocolate stick.
You can use any cocoa powder for this cake, of course the better quality it is, the better flavour it will have. Also do make sure you are using cocoa powder and not a hot chocolate powder.
For the gravestones, you could use bourbon biscuits or shortbread instead.
Although I provide cup measurements, I highly recommend weighing your ingredients out using digital kitchen scales. It is the most accurate way to measure ingredients and will ensure the best results. Digital scales are very low cost and can be purchased for around £12 ($16.50).
For teaspoon (tsp) and tablespoon (tbsp) measurements, please use measuring spoons and not the type of spoons you eat with. Again this will ensure accuracy and provide the best results.
If you want to make this cake in a 9" square tin you will need: