Put all ingredients into a large mixing bowl and use an electric hand mixer. Spoon into the cases equally.
Put in the oven and bake for 15-20 minutes until the cupcakes are cooked and golden on top. As soon as possible, take the cupcakes in their cases out of the tin and let cool, on a wire rack.
For buttercream icing mix butter with the icing sugar and add the orange extract. Continue to mix until smooth adding the milk to loosen the buttercream.
Split the buttercream into 2 bowls and using food colouring, colour one blue and the other orange.
Use a small amount of coloured buttercream and spread it the using a palette knife on top of the cupcakes, creating a nice flat surface and smooth gently with the palette knife. Don’t worry too much as most of the buttercream will be covered. You will have 6 orange and 6 blue cupcakes.
Place a large marshmallow in the centre of each cake to help create some height.
Take a freezer bag, fill it with the orange buttercream, let out the excess air, seal, then snip off 1/8th of an inch from the corner. Take a cupcake and squeeze liberally all over the marshmallow letting the string of buttercream fall on top of itself like a tangled ball of string, completely covering the marshmallow! Do this to 6 of the cupcakes.
For the spikey design, starting at the outer edge, touch the tip of the bag to the surface of the cupcake, squeeze gently and pull away to create a spike. Repeat around the edge of the cake, and make a second row next to the marshmallow if necessary. Now carry on and build up layers so you completely cover the marshmallow, be as neat or as random as you like. Repeat these methods for the 6 remaining cupcakes.
Take some white mini marshmallows and thread onto cocktail sticks, wet the flat end with a little water and push a chocolate chip on to create an eye.
Push the cocktail sticks into the cakes at various angles, to make some scary looking monsters.